avcodec/mpegvideo: Move decoding-only code into a new file

This will allow to disable this code altogether when
all decoders are disabled.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

4 files changed, 612 insertions, 577 deletions

diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index 81a11a3688..fc07308615 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -125,7 +125,7 @@ OBJS-$(CONFIG_MPEGAUDIODSP)            += mpegaudiodsp.o                \
                                           mpegaudiodsp_float.o
 OBJS-$(CONFIG_MPEGAUDIOHEADER)         += mpegaudiodecheader.o mpegaudiotabs.o
 OBJS-$(CONFIG_MPEG4AUDIO)              += mpeg4audio.o mpeg4audio_sample_rates.o
-OBJS-$(CONFIG_MPEGVIDEO)               += mpegvideo.o mpegvideodsp.o rl.o \
+OBJS-$(CONFIG_MPEGVIDEO)               += mpegvideo.o mpegvideo_dec.o mpegvideodsp.o rl.o \
                                           mpegvideo_motion.o mpegutils.o \
                                           mpegvideodata.o mpegpicture.o  \
                                           to_upper4.o
diff --git a/libavcodec/mpegvideo.c b/libavcodec/mpegvideo.c
index d34dadf939..a2c4e14b6e 100644
--- a/libavcodec/mpegvideo.c
+++ b/libavcodec/mpegvideo.c
@@ -31,13 +31,11 @@
 #include "libavutil/avassert.h"
 #include "libavutil/imgutils.h"
 #include "libavutil/internal.h"
-#include "libavutil/video_enc_params.h"
 
 #include "avcodec.h"
 #include "blockdsp.h"
 #include "h264chroma.h"
 #include "idctdsp.h"
-#include "internal.h"
 #include "mathops.h"
 #include "mpeg_er.h"
 #include "mpegutils.h"
@@ -345,14 +343,6 @@ av_cold void ff_mpv_idct_init(MpegEncContext *s)
     ff_init_scantable(s->idsp.idct_permutation, &s->intra_v_scantable, ff_alternate_vertical_scan);
 }
 
-static int alloc_picture(MpegEncContext *s, Picture *pic)
-{
-    return ff_alloc_picture(s->avctx, pic, &s->me, &s->sc, 0, 0,
-                            s->chroma_x_shift, s->chroma_y_shift, s->out_format,
-                            s->mb_stride, s->mb_width, s->mb_height, s->b8_stride,
-                            &s->linesize, &s->uvlinesize);
-}
-
 static int init_duplicate_context(MpegEncContext *s)
 {
     int y_size = s->b8_stride * (2 * s->mb_height + 1);
@@ -403,12 +393,7 @@ static int init_duplicate_context(MpegEncContext *s)
     return 0;
 }
 
-/**
- * Initialize an MpegEncContext's thread contexts. Presumes that
- * slice_context_count is already set and that all the fields
- * that are freed/reset in free_duplicate_context() are NULL.
- */
-static int init_duplicate_contexts(MpegEncContext *s)
+int ff_mpv_init_duplicate_contexts(MpegEncContext *s)
 {
     int nb_slices = s->slice_context_count, ret;
 
@@ -518,146 +503,6 @@ int ff_update_duplicate_context(MpegEncContext *dst, MpegEncContext *src)
     return 0;
 }
 
-int ff_mpeg_update_thread_context(AVCodecContext *dst,
-                                  const AVCodecContext *src)
-{
-    int i, ret;
-    MpegEncContext *s = dst->priv_data, *s1 = src->priv_data;
-
-    if (dst == src)
-        return 0;
-
-    av_assert0(s != s1);
-
-    // FIXME can parameters change on I-frames?
-    // in that case dst may need a reinit
-    if (!s->context_initialized) {
-        int err;
-        memcpy(s, s1, sizeof(MpegEncContext));
-
-        s->avctx                 = dst;
-        s->bitstream_buffer      = NULL;
-        s->bitstream_buffer_size = s->allocated_bitstream_buffer_size = 0;
-
-        if (s1->context_initialized){
-//             s->picture_range_start  += MAX_PICTURE_COUNT;
-//             s->picture_range_end    += MAX_PICTURE_COUNT;
-            ff_mpv_idct_init(s);
-            if((err = ff_mpv_common_init(s)) < 0){
-                memset(s, 0, sizeof(MpegEncContext));
-                s->avctx = dst;
-                return err;
-            }
-        }
-    }
-
-    if (s->height != s1->height || s->width != s1->width || s->context_reinit) {
-        s->height = s1->height;
-        s->width  = s1->width;
-        if ((ret = ff_mpv_common_frame_size_change(s)) < 0)
-            return ret;
-    }
-
-    s->avctx->coded_height  = s1->avctx->coded_height;
-    s->avctx->coded_width   = s1->avctx->coded_width;
-    s->avctx->width         = s1->avctx->width;
-    s->avctx->height        = s1->avctx->height;
-
-    s->quarter_sample       = s1->quarter_sample;
-
-    s->coded_picture_number = s1->coded_picture_number;
-    s->picture_number       = s1->picture_number;
-
-    av_assert0(!s->picture || s->picture != s1->picture);
-    if(s->picture)
-    for (i = 0; i < MAX_PICTURE_COUNT; i++) {
-        ff_mpeg_unref_picture(s->avctx, &s->picture[i]);
-        if (s1->picture && s1->picture[i].f->buf[0] &&
-            (ret = ff_mpeg_ref_picture(s->avctx, &s->picture[i], &s1->picture[i])) < 0)
-            return ret;
-    }
-
-#define UPDATE_PICTURE(pic)\
-do {\
-    ff_mpeg_unref_picture(s->avctx, &s->pic);\
-    if (s1->pic.f && s1->pic.f->buf[0])\
-        ret = ff_mpeg_ref_picture(s->avctx, &s->pic, &s1->pic);\
-    else\
-        ret = ff_update_picture_tables(&s->pic, &s1->pic);\
-    if (ret < 0)\
-        return ret;\
-} while (0)
-
-    UPDATE_PICTURE(current_picture);
-    UPDATE_PICTURE(last_picture);
-    UPDATE_PICTURE(next_picture);
-
-#define REBASE_PICTURE(pic, new_ctx, old_ctx)                                 \
-    ((pic && pic >= old_ctx->picture &&                                       \
-      pic < old_ctx->picture + MAX_PICTURE_COUNT) ?                           \
-        &new_ctx->picture[pic - old_ctx->picture] : NULL)
-
-    s->last_picture_ptr    = REBASE_PICTURE(s1->last_picture_ptr,    s, s1);
-    s->current_picture_ptr = REBASE_PICTURE(s1->current_picture_ptr, s, s1);
-    s->next_picture_ptr    = REBASE_PICTURE(s1->next_picture_ptr,    s, s1);
-
-    // Error/bug resilience
-    s->next_p_frame_damaged = s1->next_p_frame_damaged;
-    s->workaround_bugs      = s1->workaround_bugs;
-    s->padding_bug_score    = s1->padding_bug_score;
-
-    // MPEG-4 timing info
-    memcpy(&s->last_time_base, &s1->last_time_base,
-           (char *) &s1->pb_field_time + sizeof(s1->pb_field_time) -
-           (char *) &s1->last_time_base);
-
-    // B-frame info
-    s->max_b_frames = s1->max_b_frames;
-    s->low_delay    = s1->low_delay;
-    s->droppable    = s1->droppable;
-
-    // DivX handling (doesn't work)
-    s->divx_packed  = s1->divx_packed;
-
-    if (s1->bitstream_buffer) {
-        if (s1->bitstream_buffer_size +
-            AV_INPUT_BUFFER_PADDING_SIZE > s->allocated_bitstream_buffer_size) {
-            av_fast_malloc(&s->bitstream_buffer,
-                           &s->allocated_bitstream_buffer_size,
-                           s1->allocated_bitstream_buffer_size);
-            if (!s->bitstream_buffer) {
-                s->bitstream_buffer_size = 0;
-                return AVERROR(ENOMEM);
-            }
-        }
-        s->bitstream_buffer_size = s1->bitstream_buffer_size;
-        memcpy(s->bitstream_buffer, s1->bitstream_buffer,
-               s1->bitstream_buffer_size);
-        memset(s->bitstream_buffer + s->bitstream_buffer_size, 0,
-               AV_INPUT_BUFFER_PADDING_SIZE);
-    }
-
-    // linesize-dependent scratch buffer allocation
-    if (!s->sc.edge_emu_buffer)
-        if (s1->linesize) {
-            if (ff_mpeg_framesize_alloc(s->avctx, &s->me,
-                                        &s->sc, s1->linesize) < 0) {
-                av_log(s->avctx, AV_LOG_ERROR, "Failed to allocate context "
-                       "scratch buffers.\n");
-                return AVERROR(ENOMEM);
-            }
-        } else {
-            av_log(s->avctx, AV_LOG_ERROR, "Context scratch buffers could not "
-                   "be allocated due to unknown size.\n");
-        }
-
-    // MPEG-2/interlacing info
-    memcpy(&s->progressive_sequence, &s1->progressive_sequence,
-           (char *) &s1->rtp_mode - (char *) &s1->progressive_sequence);
-
-    return 0;
-}
-
 /**
  * Set the given MpegEncContext to common defaults
  * (same for encoding and decoding).
@@ -682,29 +527,7 @@ void ff_mpv_common_defaults(MpegEncContext *s)
     s->slice_context_count   = 1;
 }
 
-/**
- * Initialize the given MpegEncContext for decoding.
- * the changed fields will not depend upon
- * the prior state of the MpegEncContext.
- */
-void ff_mpv_decode_init(MpegEncContext *s, AVCodecContext *avctx)
-{
-    ff_mpv_common_defaults(s);
-
-    s->avctx           = avctx;
-    s->width           = avctx->coded_width;
-    s->height          = avctx->coded_height;
-    s->codec_id        = avctx->codec->id;
-    s->workaround_bugs = avctx->workaround_bugs;
-
-    /* convert fourcc to upper case */
-    s->codec_tag       = ff_toupper4(avctx->codec_tag);
-}
-
-/**
- * Initialize and allocates MpegEncContext fields dependent on the resolution.
- */
-static int init_context_frame(MpegEncContext *s)
+int ff_mpv_init_context_frame(MpegEncContext *s)
 {
     int y_size, c_size, yc_size, i, mb_array_size, mv_table_size, x, y;
 
@@ -981,7 +804,7 @@ av_cold int ff_mpv_common_init(MpegEncContext *s)
         !(s->new_picture.f     = av_frame_alloc()))
         goto fail_nomem;
 
-    if ((ret = init_context_frame(s)))
+    if ((ret = ff_mpv_init_context_frame(s)))
         goto fail;
 
 #if FF_API_FLAG_TRUNCATED
@@ -994,7 +817,7 @@ av_cold int ff_mpv_common_init(MpegEncContext *s)
     s->slice_context_count = nb_slices;
 
 //     if (s->width && s->height) {
-    ret = init_duplicate_contexts(s);
+    ret = ff_mpv_init_duplicate_contexts(s);
     if (ret < 0)
         goto fail;
 //     }
@@ -1007,13 +830,7 @@ av_cold int ff_mpv_common_init(MpegEncContext *s)
     return ret;
 }
 
-/**
- * Frees and resets MpegEncContext fields depending on the resolution
- * as well as the slice thread contexts.
- * Is used during resolution changes to avoid a full reinitialization of the
- * codec.
- */
-static void free_context_frame(MpegEncContext *s)
+void ff_mpv_free_context_frame(MpegEncContext *s)
 {
     int i, j, k;
 
@@ -1066,61 +883,6 @@ static void free_context_frame(MpegEncContext *s)
     s->linesize = s->uvlinesize = 0;
 }
 
-int ff_mpv_common_frame_size_change(MpegEncContext *s)
-{
-    int i, err = 0;
-
-    if (!s->context_initialized)
-        return AVERROR(EINVAL);
-
-    free_context_frame(s);
-
-    if (s->picture)
-        for (i = 0; i < MAX_PICTURE_COUNT; i++) {
-                s->picture[i].needs_realloc = 1;
-        }
-
-    s->last_picture_ptr         =
-    s->next_picture_ptr         =
-    s->current_picture_ptr      = NULL;
-
-    // init
-    if (s->codec_id == AV_CODEC_ID_MPEG2VIDEO && !s->progressive_sequence)
-        s->mb_height = (s->height + 31) / 32 * 2;
-    else
-        s->mb_height = (s->height + 15) / 16;
-
-    if ((s->width || s->height) &&
-        (err = av_image_check_size(s->width, s->height, 0, s->avctx)) < 0)
-        goto fail;
-
-    /* set chroma shifts */
-    err = av_pix_fmt_get_chroma_sub_sample(s->avctx->pix_fmt,
-                                           &s->chroma_x_shift,
-                                           &s->chroma_y_shift);
-    if (err < 0)
-        goto fail;
-
-    if ((err = init_context_frame(s)))
-        goto fail;
-
-    memset(s->thread_context, 0, sizeof(s->thread_context));
-    s->thread_context[0]   = s;
-
-    if (s->width && s->height) {
-        err = init_duplicate_contexts(s);
-        if (err < 0)
-            goto fail;
-    }
-    s->context_reinit = 0;
-
-    return 0;
- fail:
-    free_context_frame(s);
-    s->context_reinit = 1;
-    return err;
-}
-
 /* init common structure for both encoder and decoder */
 void ff_mpv_common_end(MpegEncContext *s)
 {
@@ -1129,7 +891,7 @@ void ff_mpv_common_end(MpegEncContext *s)
     if (!s)
         return;
 
-    free_context_frame(s);
+    ff_mpv_free_context_frame(s);
     if (s->slice_context_count > 1)
         s->slice_context_count = 1;
 
@@ -1174,296 +936,6 @@ void ff_mpv_common_end(MpegEncContext *s)
 }
 
 
-static void gray_frame(AVFrame *frame)
-{
-    int i, h_chroma_shift, v_chroma_shift;
-
-    av_pix_fmt_get_chroma_sub_sample(frame->format, &h_chroma_shift, &v_chroma_shift);
-
-    for(i=0; i<frame->height; i++)
-        memset(frame->data[0] + frame->linesize[0]*i, 0x80, frame->width);
-    for(i=0; i<AV_CEIL_RSHIFT(frame->height, v_chroma_shift); i++) {
-        memset(frame->data[1] + frame->linesize[1]*i,
-               0x80, AV_CEIL_RSHIFT(frame->width, h_chroma_shift));
-        memset(frame->data[2] + frame->linesize[2]*i,
-               0x80, AV_CEIL_RSHIFT(frame->width, h_chroma_shift));
-    }
-}
-
-/**
- * generic function called after decoding
- * the header and before a frame is decoded.
- */
-int ff_mpv_frame_start(MpegEncContext *s, AVCodecContext *avctx)
-{
-    int i, ret;
-    Picture *pic;
-    s->mb_skipped = 0;
-
-    if (!ff_thread_can_start_frame(avctx)) {
-        av_log(avctx, AV_LOG_ERROR, "Attempt to start a frame outside SETUP state\n");
-        return -1;
-    }
-
-    /* mark & release old frames */
-    if (s->pict_type != AV_PICTURE_TYPE_B && s->last_picture_ptr &&
-        s->last_picture_ptr != s->next_picture_ptr &&
-        s->last_picture_ptr->f->buf[0]) {
-        ff_mpeg_unref_picture(s->avctx, s->last_picture_ptr);
-    }
-
-    /* release forgotten pictures */
-    /* if (MPEG-124 / H.263) */
-    for (i = 0; i < MAX_PICTURE_COUNT; i++) {
-        if (&s->picture[i] != s->last_picture_ptr &&
-            &s->picture[i] != s->next_picture_ptr &&
-            s->picture[i].reference && !s->picture[i].needs_realloc) {
-            ff_mpeg_unref_picture(s->avctx, &s->picture[i]);
-        }
-    }
-
-    ff_mpeg_unref_picture(s->avctx, &s->current_picture);
-    ff_mpeg_unref_picture(s->avctx, &s->last_picture);
-    ff_mpeg_unref_picture(s->avctx, &s->next_picture);
-
-    /* release non reference frames */
-    for (i = 0; i < MAX_PICTURE_COUNT; i++) {
-        if (!s->picture[i].reference)
-            ff_mpeg_unref_picture(s->avctx, &s->picture[i]);
-    }
-
-    if (s->current_picture_ptr && !s->current_picture_ptr->f->buf[0]) {
-        // we already have an unused image
-        // (maybe it was set before reading the header)
-        pic = s->current_picture_ptr;
-    } else {
-        i   = ff_find_unused_picture(s->avctx, s->picture, 0);
-        if (i < 0) {
-            av_log(s->avctx, AV_LOG_ERROR, "no frame buffer available\n");
-            return i;
-        }
-        pic = &s->picture[i];
-    }
-
-    pic->reference = 0;
-    if (!s->droppable) {
-        if (s->pict_type != AV_PICTURE_TYPE_B)
-            pic->reference = 3;
-    }
-
-    pic->f->coded_picture_number = s->coded_picture_number++;
-
-    if (alloc_picture(s, pic) < 0)
-        return -1;
-
-    s->current_picture_ptr = pic;
-    // FIXME use only the vars from current_pic
-    s->current_picture_ptr->f->top_field_first = s->top_field_first;
-    if (s->codec_id == AV_CODEC_ID_MPEG1VIDEO ||
-        s->codec_id == AV_CODEC_ID_MPEG2VIDEO) {
-        if (s->picture_structure != PICT_FRAME)
-            s->current_picture_ptr->f->top_field_first =
-                (s->picture_structure == PICT_TOP_FIELD) == s->first_field;
-    }
-    s->current_picture_ptr->f->interlaced_frame = !s->progressive_frame &&
-                                                 !s->progressive_sequence;
-    s->current_picture_ptr->field_picture      =  s->picture_structure != PICT_FRAME;
-
-    s->current_picture_ptr->f->pict_type = s->pict_type;
-    // if (s->avctx->flags && AV_CODEC_FLAG_QSCALE)
-    //     s->current_picture_ptr->quality = s->new_picture_ptr->quality;
-    s->current_picture_ptr->f->key_frame = s->pict_type == AV_PICTURE_TYPE_I;
-
-    if ((ret = ff_mpeg_ref_picture(s->avctx, &s->current_picture,
-                                   s->current_picture_ptr)) < 0)
-        return ret;
-
-    if (s->pict_type != AV_PICTURE_TYPE_B) {
-        s->last_picture_ptr = s->next_picture_ptr;
-        if (!s->droppable)
-            s->next_picture_ptr = s->current_picture_ptr;
-    }
-    ff_dlog(s->avctx, "L%p N%p C%p L%p N%p C%p type:%d drop:%d\n",
-            s->last_picture_ptr, s->next_picture_ptr,s->current_picture_ptr,
-            s->last_picture_ptr    ? s->last_picture_ptr->f->data[0]    : NULL,
-            s->next_picture_ptr    ? s->next_picture_ptr->f->data[0]    : NULL,
-            s->current_picture_ptr ? s->current_picture_ptr->f->data[0] : NULL,
-            s->pict_type, s->droppable);
-
-    if ((!s->last_picture_ptr || !s->last_picture_ptr->f->buf[0]) &&
-        (s->pict_type != AV_PICTURE_TYPE_I)) {
-        int h_chroma_shift, v_chroma_shift;
-        av_pix_fmt_get_chroma_sub_sample(s->avctx->pix_fmt,
-                                         &h_chroma_shift, &v_chroma_shift);
-        if (s->pict_type == AV_PICTURE_TYPE_B && s->next_picture_ptr && s->next_picture_ptr->f->buf[0])
-            av_log(avctx, AV_LOG_DEBUG,
-                   "allocating dummy last picture for B frame\n");
-        else if (s->pict_type != AV_PICTURE_TYPE_I)
-            av_log(avctx, AV_LOG_ERROR,
-                   "warning: first frame is no keyframe\n");
-
-        /* Allocate a dummy frame */
-        i = ff_find_unused_picture(s->avctx, s->picture, 0);
-        if (i < 0) {
-            av_log(s->avctx, AV_LOG_ERROR, "no frame buffer available\n");
-            return i;
-        }
-        s->last_picture_ptr = &s->picture[i];
-
-        s->last_picture_ptr->reference   = 3;
-        s->last_picture_ptr->f->key_frame = 0;
-        s->last_picture_ptr->f->pict_type = AV_PICTURE_TYPE_P;
-
-        if (alloc_picture(s, s->last_picture_ptr) < 0) {
-            s->last_picture_ptr = NULL;
-            return -1;
-        }
-
-        if (!avctx->hwaccel) {
-            for(i=0; i<avctx->height; i++)
-                memset(s->last_picture_ptr->f->data[0] + s->last_picture_ptr->f->linesize[0]*i,
-                       0x80, avctx->width);
-            if (s->last_picture_ptr->f->data[2]) {
-                for(i=0; i<AV_CEIL_RSHIFT(avctx->height, v_chroma_shift); i++) {
-                    memset(s->last_picture_ptr->f->data[1] + s->last_picture_ptr->f->linesize[1]*i,
-                        0x80, AV_CEIL_RSHIFT(avctx->width, h_chroma_shift));
-                    memset(s->last_picture_ptr->f->data[2] + s->last_picture_ptr->f->linesize[2]*i,
-                        0x80, AV_CEIL_RSHIFT(avctx->width, h_chroma_shift));
-                }
-            }
-
-            if(s->codec_id == AV_CODEC_ID_FLV1 || s->codec_id == AV_CODEC_ID_H263){
-                for(i=0; i<avctx->height; i++)
-                memset(s->last_picture_ptr->f->data[0] + s->last_picture_ptr->f->linesize[0]*i, 16, avctx->width);
-            }
-        }
-
-        ff_thread_report_progress(&s->last_picture_ptr->tf, INT_MAX, 0);
-        ff_thread_report_progress(&s->last_picture_ptr->tf, INT_MAX, 1);
-    }
-    if ((!s->next_picture_ptr || !s->next_picture_ptr->f->buf[0]) &&
-        s->pict_type == AV_PICTURE_TYPE_B) {
-        /* Allocate a dummy frame */
-        i = ff_find_unused_picture(s->avctx, s->picture, 0);
-        if (i < 0) {
-            av_log(s->avctx, AV_LOG_ERROR, "no frame buffer available\n");
-            return i;
-        }
-        s->next_picture_ptr = &s->picture[i];
-
-        s->next_picture_ptr->reference   = 3;
-        s->next_picture_ptr->f->key_frame = 0;
-        s->next_picture_ptr->f->pict_type = AV_PICTURE_TYPE_P;
-
-        if (alloc_picture(s, s->next_picture_ptr) < 0) {
-            s->next_picture_ptr = NULL;
-            return -1;
-        }
-        ff_thread_report_progress(&s->next_picture_ptr->tf, INT_MAX, 0);
-        ff_thread_report_progress(&s->next_picture_ptr->tf, INT_MAX, 1);
-    }
-
-#if 0 // BUFREF-FIXME
-    memset(s->last_picture.f->data, 0, sizeof(s->last_picture.f->data));
-    memset(s->next_picture.f->data, 0, sizeof(s->next_picture.f->data));
-#endif
-    if (s->last_picture_ptr) {
-        if (s->last_picture_ptr->f->buf[0] &&
-            (ret = ff_mpeg_ref_picture(s->avctx, &s->last_picture,
-                                       s->last_picture_ptr)) < 0)
-            return ret;
-    }
-    if (s->next_picture_ptr) {
-        if (s->next_picture_ptr->f->buf[0] &&
-            (ret = ff_mpeg_ref_picture(s->avctx, &s->next_picture,
-                                       s->next_picture_ptr)) < 0)
-            return ret;
-    }
-
-    av_assert0(s->pict_type == AV_PICTURE_TYPE_I || (s->last_picture_ptr &&
-                                                 s->last_picture_ptr->f->buf[0]));
-
-    if (s->picture_structure!= PICT_FRAME) {
-        int i;
-        for (i = 0; i < 4; i++) {
-            if (s->picture_structure == PICT_BOTTOM_FIELD) {
-                s->current_picture.f->data[i] +=
-                    s->current_picture.f->linesize[i];
-            }
-            s->current_picture.f->linesize[i] *= 2;
-            s->last_picture.f->linesize[i]    *= 2;
-            s->next_picture.f->linesize[i]    *= 2;
-        }
-    }
-
-    /* set dequantizer, we can't do it during init as
-     * it might change for MPEG-4 and we can't do it in the header
-     * decode as init is not called for MPEG-4 there yet */
-    if (s->mpeg_quant || s->codec_id == AV_CODEC_ID_MPEG2VIDEO) {
-        s->dct_unquantize_intra = s->dct_unquantize_mpeg2_intra;
-        s->dct_unquantize_inter = s->dct_unquantize_mpeg2_inter;
-    } else if (s->out_format == FMT_H263 || s->out_format == FMT_H261) {
-        s->dct_unquantize_intra = s->dct_unquantize_h263_intra;
-        s->dct_unquantize_inter = s->dct_unquantize_h263_inter;
-    } else {
-        s->dct_unquantize_intra = s->dct_unquantize_mpeg1_intra;
-        s->dct_unquantize_inter = s->dct_unquantize_mpeg1_inter;
-    }
-
-    if (s->avctx->debug & FF_DEBUG_NOMC) {
-        gray_frame(s->current_picture_ptr->f);
-    }
-
-    return 0;
-}
-
-/* called after a frame has been decoded. */
-void ff_mpv_frame_end(MpegEncContext *s)
-{
-    emms_c();
-
-    if (s->current_picture.reference)
-        ff_thread_report_progress(&s->current_picture_ptr->tf, INT_MAX, 0);
-}
-
-void ff_print_debug_info(MpegEncContext *s, Picture *p, AVFrame *pict)
-{
-    ff_print_debug_info2(s->avctx, pict, s->mbskip_table, p->mb_type,
-                         p->qscale_table, p->motion_val,
-                         s->mb_width, s->mb_height, s->mb_stride, s->quarter_sample);
-}
-
-int ff_mpv_export_qp_table(MpegEncContext *s, AVFrame *f, Picture *p, int qp_type)
-{
-    AVVideoEncParams *par;
-    int mult = (qp_type == FF_QSCALE_TYPE_MPEG1) ? 2 : 1;
-    unsigned int nb_mb = p->alloc_mb_height * p->alloc_mb_width;
-    unsigned int x, y;
-
-    if (!(s->avctx->export_side_data & AV_CODEC_EXPORT_DATA_VIDEO_ENC_PARAMS))
-        return 0;
-
-    par = av_video_enc_params_create_side_data(f, AV_VIDEO_ENC_PARAMS_MPEG2, nb_mb);
-    if (!par)
-        return AVERROR(ENOMEM);
-
-    for (y = 0; y < p->alloc_mb_height; y++)
-        for (x = 0; x < p->alloc_mb_width; x++) {
-            const unsigned int block_idx = y * p->alloc_mb_width + x;
-            const unsigned int     mb_xy = y * p->alloc_mb_stride + x;
-            AVVideoBlockParams *b = av_video_enc_params_block(par, block_idx);
-
-            b->src_x = x * 16;
-            b->src_y = y * 16;
-            b->w     = 16;
-            b->h     = 16;
-
-            b->delta_qp = p->qscale_table[mb_xy] * mult;
-        }
-
-    return 0;
-}
-
 static inline int hpel_motion_lowres(MpegEncContext *s,
                                      uint8_t *dest, uint8_t *src,
                                      int field_based, int field_select,
@@ -2274,13 +1746,6 @@ void ff_mpv_reconstruct_mb(MpegEncContext *s, int16_t block[12][64])
     else                  mpv_reconstruct_mb_internal(s, block, 0, 0);
 }
 
-void ff_mpeg_draw_horiz_band(MpegEncContext *s, int y, int h)
-{
-    ff_draw_horiz_band(s->avctx, s->current_picture_ptr->f,
-                       s->last_picture_ptr ? s->last_picture_ptr->f : NULL, y, h, s->picture_structure,
-                       s->first_field, s->low_delay);
-}
-
 void ff_init_block_index(MpegEncContext *s){ //FIXME maybe rename
     const int linesize   = s->current_picture.f->linesize[0]; //not s->linesize as this would be wrong for field pics
     const int uvlinesize = s->current_picture.f->linesize[1];
@@ -2314,35 +1779,6 @@ void ff_init_block_index(MpegEncContext *s){ //FIXME maybe rename
     }
 }
 
-void ff_mpeg_flush(AVCodecContext *avctx){
-    int i;
-    MpegEncContext *s = avctx->priv_data;
-
-    if (!s->picture)
-        return;
-
-    for (i = 0; i < MAX_PICTURE_COUNT; i++)
-        ff_mpeg_unref_picture(s->avctx, &s->picture[i]);
-    s->current_picture_ptr = s->last_picture_ptr = s->next_picture_ptr = NULL;
-
-    ff_mpeg_unref_picture(s->avctx, &s->current_picture);
-    ff_mpeg_unref_picture(s->avctx, &s->last_picture);
-    ff_mpeg_unref_picture(s->avctx, &s->next_picture);
-
-    s->mb_x= s->mb_y= 0;
-
-#if FF_API_FLAG_TRUNCATED
-    s->parse_context.state= -1;
-    s->parse_context.frame_start_found= 0;
-    s->parse_context.overread= 0;
-    s->parse_context.overread_index= 0;
-    s->parse_context.index= 0;
-    s->parse_context.last_index= 0;
-#endif
-    s->bitstream_buffer_size=0;
-    s->pp_time=0;
-}
-
 /**
  * set qscale and update qscale dependent variables.
  */
@@ -2359,9 +1795,3 @@ void ff_set_qscale(MpegEncContext * s, int qscale)
     s->y_dc_scale= s->y_dc_scale_table[ qscale ];
     s->c_dc_scale= s->c_dc_scale_table[ s->chroma_qscale ];
 }
-
-void ff_mpv_report_decode_progress(MpegEncContext *s)
-{
-    if (s->pict_type != AV_PICTURE_TYPE_B && !s->partitioned_frame && !s->er.error_occurred)
-        ff_thread_report_progress(&s->current_picture_ptr->tf, s->mb_y, 0);
-}
diff --git a/libavcodec/mpegvideo.h b/libavcodec/mpegvideo.h
index fabcce2436..1c14f5b0f0 100644
--- a/libavcodec/mpegvideo.h
+++ b/libavcodec/mpegvideo.h
@@ -679,10 +679,32 @@ void ff_mpv_common_init_neon(MpegEncContext *s);
 void ff_mpv_common_init_ppc(MpegEncContext *s);
 void ff_mpv_common_init_x86(MpegEncContext *s);
 void ff_mpv_common_init_mips(MpegEncContext *s);
+/**
+ * Initialize an MpegEncContext's thread contexts. Presumes that
+ * slice_context_count is already set and that all the fields
+ * that are freed/reset in free_duplicate_context() are NULL.
+ */
+int ff_mpv_init_duplicate_contexts(MpegEncContext *s);
+/**
+ * Initialize and allocates MpegEncContext fields dependent on the resolution.
+ */
+int ff_mpv_init_context_frame(MpegEncContext *s);
+/**
+ * Frees and resets MpegEncContext fields depending on the resolution
+ * as well as the slice thread contexts.
+ * Is used during resolution changes to avoid a full reinitialization of the
+ * codec.
+ */
+void ff_mpv_free_context_frame(MpegEncContext *s);
 
 int ff_mpv_common_frame_size_change(MpegEncContext *s);
 void ff_mpv_common_end(MpegEncContext *s);
 
+/**
+ * Initialize the given MpegEncContext for decoding.
+ * the changed fields will not depend upon
+ * the prior state of the MpegEncContext.
+ */
 void ff_mpv_decode_init(MpegEncContext *s, AVCodecContext *avctx);
 void ff_mpv_reconstruct_mb(MpegEncContext *s, int16_t block[12][64]);
 void ff_mpv_report_decode_progress(MpegEncContext *s);
diff --git a/libavcodec/mpegvideo_dec.c b/libavcodec/mpegvideo_dec.c
new file mode 100644
index 0000000000..8b625d2835
--- /dev/null
+++ b/libavcodec/mpegvideo_dec.c
@@ -0,0 +1,583 @@
+/*
+ * Common mpeg video decoding code
+ * Copyright (c) 2000,2001 Fabrice Bellard
+ * Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <limits.h>
+
+#include "libavutil/avassert.h"
+#include "libavutil/imgutils.h"
+#include "libavutil/internal.h"
+#include "libavutil/video_enc_params.h"
+
+#include "avcodec.h"
+#include "internal.h"
+#include "mpegutils.h"
+#include "mpegvideo.h"
+#include "thread.h"
+
+void ff_mpv_decode_init(MpegEncContext *s, AVCodecContext *avctx)
+{
+    ff_mpv_common_defaults(s);
+
+    s->avctx           = avctx;
+    s->width           = avctx->coded_width;
+    s->height          = avctx->coded_height;
+    s->codec_id        = avctx->codec->id;
+    s->workaround_bugs = avctx->workaround_bugs;
+
+    /* convert fourcc to upper case */
+    s->codec_tag       = ff_toupper4(avctx->codec_tag);
+}
+
+int ff_mpeg_update_thread_context(AVCodecContext *dst,
+                                  const AVCodecContext *src)
+{
+    MpegEncContext *const s1 = src->priv_data;
+    MpegEncContext *const s  = dst->priv_data;
+    int ret;
+
+    if (dst == src)
+        return 0;
+
+    av_assert0(s != s1);
+
+    // FIXME can parameters change on I-frames?
+    // in that case dst may need a reinit
+    if (!s->context_initialized) {
+        int err;
+        memcpy(s, s1, sizeof(*s));
+
+        s->avctx                 = dst;
+        s->bitstream_buffer      = NULL;
+        s->bitstream_buffer_size = s->allocated_bitstream_buffer_size = 0;
+
+        if (s1->context_initialized) {
+//             s->picture_range_start  += MAX_PICTURE_COUNT;
+//             s->picture_range_end    += MAX_PICTURE_COUNT;
+            ff_mpv_idct_init(s);
+            if ((err = ff_mpv_common_init(s)) < 0) {
+                memset(s, 0, sizeof(*s));
+                s->avctx = dst;
+                return err;
+            }
+        }
+    }
+
+    if (s->height != s1->height || s->width != s1->width || s->context_reinit) {
+        s->height = s1->height;
+        s->width  = s1->width;
+        if ((ret = ff_mpv_common_frame_size_change(s)) < 0)
+            return ret;
+    }
+
+    s->avctx->coded_height  = s1->avctx->coded_height;
+    s->avctx->coded_width   = s1->avctx->coded_width;
+    s->avctx->width         = s1->avctx->width;
+    s->avctx->height        = s1->avctx->height;
+
+    s->quarter_sample       = s1->quarter_sample;
+
+    s->coded_picture_number = s1->coded_picture_number;
+    s->picture_number       = s1->picture_number;
+
+    av_assert0(!s->picture || s->picture != s1->picture);
+    if (s->picture)
+        for (int i = 0; i < MAX_PICTURE_COUNT; i++) {
+            ff_mpeg_unref_picture(s->avctx, &s->picture[i]);
+            if (s1->picture && s1->picture[i].f->buf[0] &&
+                (ret = ff_mpeg_ref_picture(s->avctx, &s->picture[i], &s1->picture[i])) < 0)
+                return ret;
+        }
+
+#define UPDATE_PICTURE(pic)\
+do {\
+    ff_mpeg_unref_picture(s->avctx, &s->pic);\
+    if (s1->pic.f && s1->pic.f->buf[0])\
+        ret = ff_mpeg_ref_picture(s->avctx, &s->pic, &s1->pic);\
+    else\
+        ret = ff_update_picture_tables(&s->pic, &s1->pic);\
+    if (ret < 0)\
+        return ret;\
+} while (0)
+
+    UPDATE_PICTURE(current_picture);
+    UPDATE_PICTURE(last_picture);
+    UPDATE_PICTURE(next_picture);
+
+#define REBASE_PICTURE(pic, new_ctx, old_ctx)                                 \
+    ((pic && pic >= old_ctx->picture &&                                       \
+      pic < old_ctx->picture + MAX_PICTURE_COUNT) ?                           \
+        &new_ctx->picture[pic - old_ctx->picture] : NULL)
+
+    s->last_picture_ptr    = REBASE_PICTURE(s1->last_picture_ptr,    s, s1);
+    s->current_picture_ptr = REBASE_PICTURE(s1->current_picture_ptr, s, s1);
+    s->next_picture_ptr    = REBASE_PICTURE(s1->next_picture_ptr,    s, s1);
+
+    // Error/bug resilience
+    s->next_p_frame_damaged = s1->next_p_frame_damaged;
+    s->workaround_bugs      = s1->workaround_bugs;
+    s->padding_bug_score    = s1->padding_bug_score;
+
+    // MPEG-4 timing info
+    memcpy(&s->last_time_base, &s1->last_time_base,
+           (char *) &s1->pb_field_time + sizeof(s1->pb_field_time) -
+           (char *) &s1->last_time_base);
+
+    // B-frame info
+    s->max_b_frames = s1->max_b_frames;
+    s->low_delay    = s1->low_delay;
+    s->droppable    = s1->droppable;
+
+    // DivX handling (doesn't work)
+    s->divx_packed  = s1->divx_packed;
+
+    if (s1->bitstream_buffer) {
+        if (s1->bitstream_buffer_size +
+            AV_INPUT_BUFFER_PADDING_SIZE > s->allocated_bitstream_buffer_size) {
+            av_fast_malloc(&s->bitstream_buffer,
+                           &s->allocated_bitstream_buffer_size,
+                           s1->allocated_bitstream_buffer_size);
+            if (!s->bitstream_buffer) {
+                s->bitstream_buffer_size = 0;
+                return AVERROR(ENOMEM);
+            }
+        }
+        s->bitstream_buffer_size = s1->bitstream_buffer_size;
+        memcpy(s->bitstream_buffer, s1->bitstream_buffer,
+               s1->bitstream_buffer_size);
+        memset(s->bitstream_buffer + s->bitstream_buffer_size, 0,
+               AV_INPUT_BUFFER_PADDING_SIZE);
+    }
+
+    // linesize-dependent scratch buffer allocation
+    if (!s->sc.edge_emu_buffer)
+        if (s1->linesize) {
+            if (ff_mpeg_framesize_alloc(s->avctx, &s->me,
+                                        &s->sc, s1->linesize) < 0) {
+                av_log(s->avctx, AV_LOG_ERROR, "Failed to allocate context "
+                       "scratch buffers.\n");
+                return AVERROR(ENOMEM);
+            }
+        } else {
+            av_log(s->avctx, AV_LOG_ERROR, "Context scratch buffers could not "
+                   "be allocated due to unknown size.\n");
+        }
+
+    // MPEG-2/interlacing info
+    memcpy(&s->progressive_sequence, &s1->progressive_sequence,
+           (char *) &s1->rtp_mode - (char *) &s1->progressive_sequence);
+
+    return 0;
+}
+
+int ff_mpv_common_frame_size_change(MpegEncContext *s)
+{
+    int err = 0;
+
+    if (!s->context_initialized)
+        return AVERROR(EINVAL);
+
+    ff_mpv_free_context_frame(s);
+
+    if (s->picture)
+        for (int i = 0; i < MAX_PICTURE_COUNT; i++)
+            s->picture[i].needs_realloc = 1;
+
+    s->last_picture_ptr         =
+    s->next_picture_ptr         =
+    s->current_picture_ptr      = NULL;
+
+    // init
+    if (s->codec_id == AV_CODEC_ID_MPEG2VIDEO && !s->progressive_sequence)
+        s->mb_height = (s->height + 31) / 32 * 2;
+    else
+        s->mb_height = (s->height + 15) / 16;
+
+    if ((s->width || s->height) &&
+        (err = av_image_check_size(s->width, s->height, 0, s->avctx)) < 0)
+        goto fail;
+
+    /* set chroma shifts */
+    err = av_pix_fmt_get_chroma_sub_sample(s->avctx->pix_fmt,
+                                           &s->chroma_x_shift,
+                                           &s->chroma_y_shift);
+    if (err < 0)
+        goto fail;
+
+    if ((err = ff_mpv_init_context_frame(s)))
+        goto fail;
+
+    memset(s->thread_context, 0, sizeof(s->thread_context));
+    s->thread_context[0]   = s;
+
+    if (s->width && s->height) {
+        err = ff_mpv_init_duplicate_contexts(s);
+        if (err < 0)
+            goto fail;
+    }
+    s->context_reinit = 0;
+
+    return 0;
+ fail:
+    ff_mpv_free_context_frame(s);
+    s->context_reinit = 1;
+    return err;
+}
+
+static int alloc_picture(MpegEncContext *s, Picture *pic)
+{
+    return ff_alloc_picture(s->avctx, pic, &s->me, &s->sc, 0, 0,
+                            s->chroma_x_shift, s->chroma_y_shift, s->out_format,
+                            s->mb_stride, s->mb_width, s->mb_height, s->b8_stride,
+                            &s->linesize, &s->uvlinesize);
+}
+
+static void gray_frame(AVFrame *frame)
+{
+    int h_chroma_shift, v_chroma_shift;
+
+    av_pix_fmt_get_chroma_sub_sample(frame->format, &h_chroma_shift, &v_chroma_shift);
+
+    for (int i = 0; i < frame->height; i++)
+        memset(frame->data[0] + frame->linesize[0] * i, 0x80, frame->width);
+    for (int i = 0; i < AV_CEIL_RSHIFT(frame->height, v_chroma_shift); i++) {
+        memset(frame->data[1] + frame->linesize[1] * i,
+               0x80, AV_CEIL_RSHIFT(frame->width, h_chroma_shift));
+        memset(frame->data[2] + frame->linesize[2] * i,
+               0x80, AV_CEIL_RSHIFT(frame->width, h_chroma_shift));
+    }
+}
+
+/**
+ * generic function called after decoding
+ * the header and before a frame is decoded.
+ */
+int ff_mpv_frame_start(MpegEncContext *s, AVCodecContext *avctx)
+{
+    Picture *pic;
+    int idx, ret;
+
+    s->mb_skipped = 0;
+
+    if (!ff_thread_can_start_frame(avctx)) {
+        av_log(avctx, AV_LOG_ERROR, "Attempt to start a frame outside SETUP state\n");
+        return -1;
+    }
+
+    /* mark & release old frames */
+    if (s->pict_type != AV_PICTURE_TYPE_B && s->last_picture_ptr &&
+        s->last_picture_ptr != s->next_picture_ptr &&
+        s->last_picture_ptr->f->buf[0]) {
+        ff_mpeg_unref_picture(s->avctx, s->last_picture_ptr);
+    }
+
+    /* release forgotten pictures */
+    /* if (MPEG-124 / H.263) */
+    for (int i = 0; i < MAX_PICTURE_COUNT; i++) {
+        if (&s->picture[i] != s->last_picture_ptr &&
+            &s->picture[i] != s->next_picture_ptr &&
+            s->picture[i].reference && !s->picture[i].needs_realloc) {
+            ff_mpeg_unref_picture(s->avctx, &s->picture[i]);
+        }
+    }
+
+    ff_mpeg_unref_picture(s->avctx, &s->current_picture);
+    ff_mpeg_unref_picture(s->avctx, &s->last_picture);
+    ff_mpeg_unref_picture(s->avctx, &s->next_picture);
+
+    /* release non reference frames */
+    for (int i = 0; i < MAX_PICTURE_COUNT; i++) {
+        if (!s->picture[i].reference)
+            ff_mpeg_unref_picture(s->avctx, &s->picture[i]);
+    }
+
+    if (s->current_picture_ptr && !s->current_picture_ptr->f->buf[0]) {
+        // we already have an unused image
+        // (maybe it was set before reading the header)
+        pic = s->current_picture_ptr;
+    } else {
+        idx = ff_find_unused_picture(s->avctx, s->picture, 0);
+        if (idx < 0) {
+            av_log(s->avctx, AV_LOG_ERROR, "no frame buffer available\n");
+            return idx;
+        }
+        pic = &s->picture[idx];
+    }
+
+    pic->reference = 0;
+    if (!s->droppable) {
+        if (s->pict_type != AV_PICTURE_TYPE_B)
+            pic->reference = 3;
+    }
+
+    pic->f->coded_picture_number = s->coded_picture_number++;
+
+    if (alloc_picture(s, pic) < 0)
+        return -1;
+
+    s->current_picture_ptr = pic;
+    // FIXME use only the vars from current_pic
+    s->current_picture_ptr->f->top_field_first = s->top_field_first;
+    if (s->codec_id == AV_CODEC_ID_MPEG1VIDEO ||
+        s->codec_id == AV_CODEC_ID_MPEG2VIDEO) {
+        if (s->picture_structure != PICT_FRAME)
+            s->current_picture_ptr->f->top_field_first =
+                (s->picture_structure == PICT_TOP_FIELD) == s->first_field;
+    }
+    s->current_picture_ptr->f->interlaced_frame = !s->progressive_frame &&
+                                                 !s->progressive_sequence;
+    s->current_picture_ptr->field_picture      =  s->picture_structure != PICT_FRAME;
+
+    s->current_picture_ptr->f->pict_type = s->pict_type;
+    // if (s->avctx->flags && AV_CODEC_FLAG_QSCALE)
+    //     s->current_picture_ptr->quality = s->new_picture_ptr->quality;
+    s->current_picture_ptr->f->key_frame = s->pict_type == AV_PICTURE_TYPE_I;
+
+    if ((ret = ff_mpeg_ref_picture(s->avctx, &s->current_picture,
+                                   s->current_picture_ptr)) < 0)
+        return ret;
+
+    if (s->pict_type != AV_PICTURE_TYPE_B) {
+        s->last_picture_ptr = s->next_picture_ptr;
+        if (!s->droppable)
+            s->next_picture_ptr = s->current_picture_ptr;
+    }
+    ff_dlog(s->avctx, "L%p N%p C%p L%p N%p C%p type:%d drop:%d\n",
+            s->last_picture_ptr, s->next_picture_ptr,s->current_picture_ptr,
+            s->last_picture_ptr    ? s->last_picture_ptr->f->data[0]    : NULL,
+            s->next_picture_ptr    ? s->next_picture_ptr->f->data[0]    : NULL,
+            s->current_picture_ptr ? s->current_picture_ptr->f->data[0] : NULL,
+            s->pict_type, s->droppable);
+
+    if ((!s->last_picture_ptr || !s->last_picture_ptr->f->buf[0]) &&
+        (s->pict_type != AV_PICTURE_TYPE_I)) {
+        int h_chroma_shift, v_chroma_shift;
+        av_pix_fmt_get_chroma_sub_sample(s->avctx->pix_fmt,
+                                         &h_chroma_shift, &v_chroma_shift);
+        if (s->pict_type == AV_PICTURE_TYPE_B && s->next_picture_ptr && s->next_picture_ptr->f->buf[0])
+            av_log(avctx, AV_LOG_DEBUG,
+                   "allocating dummy last picture for B frame\n");
+        else if (s->pict_type != AV_PICTURE_TYPE_I)
+            av_log(avctx, AV_LOG_ERROR,
+                   "warning: first frame is no keyframe\n");
+
+        /* Allocate a dummy frame */
+        idx = ff_find_unused_picture(s->avctx, s->picture, 0);
+        if (idx < 0) {
+            av_log(s->avctx, AV_LOG_ERROR, "no frame buffer available\n");
+            return idx;
+        }
+        s->last_picture_ptr = &s->picture[idx];
+
+        s->last_picture_ptr->reference    = 3;
+        s->last_picture_ptr->f->key_frame = 0;
+        s->last_picture_ptr->f->pict_type = AV_PICTURE_TYPE_P;
+
+        if (alloc_picture(s, s->last_picture_ptr) < 0) {
+            s->last_picture_ptr = NULL;
+            return -1;
+        }
+
+        if (!avctx->hwaccel) {
+            for (int i = 0; i < avctx->height; i++)
+                memset(s->last_picture_ptr->f->data[0] + s->last_picture_ptr->f->linesize[0]*i,
+                       0x80, avctx->width);
+            if (s->last_picture_ptr->f->data[2]) {
+                for (int i = 0; i < AV_CEIL_RSHIFT(avctx->height, v_chroma_shift); i++) {
+                    memset(s->last_picture_ptr->f->data[1] + s->last_picture_ptr->f->linesize[1]*i,
+                        0x80, AV_CEIL_RSHIFT(avctx->width, h_chroma_shift));
+                    memset(s->last_picture_ptr->f->data[2] + s->last_picture_ptr->f->linesize[2]*i,
+                        0x80, AV_CEIL_RSHIFT(avctx->width, h_chroma_shift));
+                }
+            }
+
+            if (s->codec_id == AV_CODEC_ID_FLV1 || s->codec_id == AV_CODEC_ID_H263) {
+                for (int i = 0; i < avctx->height; i++)
+                    memset(s->last_picture_ptr->f->data[0] + s->last_picture_ptr->f->linesize[0] * i,
+                           16, avctx->width);
+            }
+        }
+
+        ff_thread_report_progress(&s->last_picture_ptr->tf, INT_MAX, 0);
+        ff_thread_report_progress(&s->last_picture_ptr->tf, INT_MAX, 1);
+    }
+    if ((!s->next_picture_ptr || !s->next_picture_ptr->f->buf[0]) &&
+        s->pict_type == AV_PICTURE_TYPE_B) {
+        /* Allocate a dummy frame */
+        idx = ff_find_unused_picture(s->avctx, s->picture, 0);
+        if (idx < 0) {
+            av_log(s->avctx, AV_LOG_ERROR, "no frame buffer available\n");
+            return idx;
+        }
+        s->next_picture_ptr = &s->picture[idx];
+
+        s->next_picture_ptr->reference   = 3;
+        s->next_picture_ptr->f->key_frame = 0;
+        s->next_picture_ptr->f->pict_type = AV_PICTURE_TYPE_P;
+
+        if (alloc_picture(s, s->next_picture_ptr) < 0) {
+            s->next_picture_ptr = NULL;
+            return -1;
+        }
+        ff_thread_report_progress(&s->next_picture_ptr->tf, INT_MAX, 0);
+        ff_thread_report_progress(&s->next_picture_ptr->tf, INT_MAX, 1);
+    }
+
+#if 0 // BUFREF-FIXME
+    memset(s->last_picture.f->data, 0, sizeof(s->last_picture.f->data));
+    memset(s->next_picture.f->data, 0, sizeof(s->next_picture.f->data));
+#endif
+    if (s->last_picture_ptr) {
+        if (s->last_picture_ptr->f->buf[0] &&
+            (ret = ff_mpeg_ref_picture(s->avctx, &s->last_picture,
+                                       s->last_picture_ptr)) < 0)
+            return ret;
+    }
+    if (s->next_picture_ptr) {
+        if (s->next_picture_ptr->f->buf[0] &&
+            (ret = ff_mpeg_ref_picture(s->avctx, &s->next_picture,
+                                       s->next_picture_ptr)) < 0)
+            return ret;
+    }
+
+    av_assert0(s->pict_type == AV_PICTURE_TYPE_I || (s->last_picture_ptr &&
+                                                 s->last_picture_ptr->f->buf[0]));
+
+    if (s->picture_structure != PICT_FRAME) {
+        for (int i = 0; i < 4; i++) {
+            if (s->picture_structure == PICT_BOTTOM_FIELD) {
+                s->current_picture.f->data[i] +=
+                    s->current_picture.f->linesize[i];
+            }
+            s->current_picture.f->linesize[i] *= 2;
+            s->last_picture.f->linesize[i]    *= 2;
+            s->next_picture.f->linesize[i]    *= 2;
+        }
+    }
+
+    /* set dequantizer, we can't do it during init as
+     * it might change for MPEG-4 and we can't do it in the header
+     * decode as init is not called for MPEG-4 there yet */
+    if (s->mpeg_quant || s->codec_id == AV_CODEC_ID_MPEG2VIDEO) {
+        s->dct_unquantize_intra = s->dct_unquantize_mpeg2_intra;
+        s->dct_unquantize_inter = s->dct_unquantize_mpeg2_inter;
+    } else if (s->out_format == FMT_H263 || s->out_format == FMT_H261) {
+        s->dct_unquantize_intra = s->dct_unquantize_h263_intra;
+        s->dct_unquantize_inter = s->dct_unquantize_h263_inter;
+    } else {
+        s->dct_unquantize_intra = s->dct_unquantize_mpeg1_intra;
+        s->dct_unquantize_inter = s->dct_unquantize_mpeg1_inter;
+    }
+
+    if (s->avctx->debug & FF_DEBUG_NOMC)
+        gray_frame(s->current_picture_ptr->f);
+
+    return 0;
+}
+
+/* called after a frame has been decoded. */
+void ff_mpv_frame_end(MpegEncContext *s)
+{
+    emms_c();
+
+    if (s->current_picture.reference)
+        ff_thread_report_progress(&s->current_picture_ptr->tf, INT_MAX, 0);
+}
+
+void ff_print_debug_info(MpegEncContext *s, Picture *p, AVFrame *pict)
+{
+    ff_print_debug_info2(s->avctx, pict, s->mbskip_table, p->mb_type,
+                         p->qscale_table, p->motion_val,
+                         s->mb_width, s->mb_height, s->mb_stride, s->quarter_sample);
+}
+
+int ff_mpv_export_qp_table(MpegEncContext *s, AVFrame *f, Picture *p, int qp_type)
+{
+    AVVideoEncParams *par;
+    int mult = (qp_type == FF_QSCALE_TYPE_MPEG1) ? 2 : 1;
+    unsigned int nb_mb = p->alloc_mb_height * p->alloc_mb_width;
+
+    if (!(s->avctx->export_side_data & AV_CODEC_EXPORT_DATA_VIDEO_ENC_PARAMS))
+        return 0;
+
+    par = av_video_enc_params_create_side_data(f, AV_VIDEO_ENC_PARAMS_MPEG2, nb_mb);
+    if (!par)
+        return AVERROR(ENOMEM);
+
+    for (unsigned y = 0; y < p->alloc_mb_height; y++)
+        for (unsigned x = 0; x < p->alloc_mb_width; x++) {
+            const unsigned int block_idx = y * p->alloc_mb_width + x;
+            const unsigned int     mb_xy = y * p->alloc_mb_stride + x;
+            AVVideoBlockParams *const b = av_video_enc_params_block(par, block_idx);
+
+            b->src_x = x * 16;
+            b->src_y = y * 16;
+            b->w     = 16;
+            b->h     = 16;
+
+            b->delta_qp = p->qscale_table[mb_xy] * mult;
+        }
+
+    return 0;
+}
+
+void ff_mpeg_draw_horiz_band(MpegEncContext *s, int y, int h)
+{
+    ff_draw_horiz_band(s->avctx, s->current_picture_ptr->f,
+                       s->last_picture_ptr ? s->last_picture_ptr->f : NULL,
+                       y, h, s->picture_structure,
+                       s->first_field, s->low_delay);
+}
+
+void ff_mpeg_flush(AVCodecContext *avctx)
+{
+    MpegEncContext *const s = avctx->priv_data;
+
+    if (!s->picture)
+        return;
+
+    for (int i = 0; i < MAX_PICTURE_COUNT; i++)
+        ff_mpeg_unref_picture(s->avctx, &s->picture[i]);
+    s->current_picture_ptr = s->last_picture_ptr = s->next_picture_ptr = NULL;
+
+    ff_mpeg_unref_picture(s->avctx, &s->current_picture);
+    ff_mpeg_unref_picture(s->avctx, &s->last_picture);
+    ff_mpeg_unref_picture(s->avctx, &s->next_picture);
+
+    s->mb_x = s->mb_y = 0;
+
+#if FF_API_FLAG_TRUNCATED
+    s->parse_context.state = -1;
+    s->parse_context.frame_start_found = 0;
+    s->parse_context.overread = 0;
+    s->parse_context.overread_index = 0;
+    s->parse_context.index = 0;
+    s->parse_context.last_index = 0;
+#endif
+    s->bitstream_buffer_size = 0;
+    s->pp_time = 0;
+}
+
+void ff_mpv_report_decode_progress(MpegEncContext *s)
+{
+    if (s->pict_type != AV_PICTURE_TYPE_B && !s->partitioned_frame && !s->er.error_occurred)
+        ff_thread_report_progress(&s->current_picture_ptr->tf, s->mb_y, 0);
+}