lavc: split LSCR decoder out of PNG decoder

It shares very little code with pngdec, so keeping them together only
makes the code harder to read.

4 files changed, 291 insertions, 169 deletions

diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index 6dda8cbb1f..0f67d8d2f6 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -439,7 +439,7 @@ OBJS-$(CONFIG_KMVC_DECODER)            += kmvc.o
 OBJS-$(CONFIG_LAGARITH_DECODER)        += lagarith.o lagarithrac.o
 OBJS-$(CONFIG_LJPEG_ENCODER)           += ljpegenc.o mjpegenc_common.o
 OBJS-$(CONFIG_LOCO_DECODER)            += loco.o
-OBJS-$(CONFIG_LSCR_DECODER)            += png.o pngdec.o pngdsp.o
+OBJS-$(CONFIG_LSCR_DECODER)            += lscrdec.o png.o pngdec.o pngdsp.o
 OBJS-$(CONFIG_M101_DECODER)            += m101.o
 OBJS-$(CONFIG_MACE3_DECODER)           += mace.o
 OBJS-$(CONFIG_MACE6_DECODER)           += mace.o
diff --git a/libavcodec/lscrdec.c b/libavcodec/lscrdec.c
new file mode 100644
index 0000000000..5ad0431534
--- /dev/null
+++ b/libavcodec/lscrdec.c
@@ -0,0 +1,279 @@
+/*
+ * 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 <stdint.h>
+#include <zlib.h>
+
+#include "libavutil/frame.h"
+#include "libavutil/error.h"
+#include "libavutil/log.h"
+
+#include "avcodec.h"
+#include "bytestream.h"
+#include "codec.h"
+#include "internal.h"
+#include "packet.h"
+#include "png.h"
+#include "pngdsp.h"
+
+typedef struct LSCRContext {
+    PNGDSPContext   dsp;
+    AVCodecContext *avctx;
+
+    AVFrame        *last_picture;
+    uint8_t        *buffer;
+    int             buffer_size;
+    uint8_t        *crow_buf;
+    int             crow_size;
+    uint8_t        *last_row;
+    unsigned int    last_row_size;
+
+    GetByteContext  gb;
+    uint8_t        *image_buf;
+    int             image_linesize;
+    int             row_size;
+    int             cur_h;
+    int             y;
+
+    z_stream        zstream;
+} LSCRContext;
+
+static void handle_row(LSCRContext *s)
+{
+    uint8_t *ptr, *last_row;
+
+    ptr = s->image_buf + s->image_linesize * s->y;
+    if (s->y == 0)
+        last_row = s->last_row;
+    else
+        last_row = ptr - s->image_linesize;
+
+    ff_png_filter_row(&s->dsp, ptr, s->crow_buf[0], s->crow_buf + 1,
+                      last_row, s->row_size, 3);
+
+    s->y++;
+}
+
+static int decode_idat(LSCRContext *s, int length)
+{
+    int ret;
+    s->zstream.avail_in = FFMIN(length, bytestream2_get_bytes_left(&s->gb));
+    s->zstream.next_in  = s->gb.buffer;
+    bytestream2_skip(&s->gb, length);
+
+    /* decode one line if possible */
+    while (s->zstream.avail_in > 0) {
+        ret = inflate(&s->zstream, Z_PARTIAL_FLUSH);
+        if (ret != Z_OK && ret != Z_STREAM_END) {
+            av_log(s->avctx, AV_LOG_ERROR, "inflate returned error %d\n", ret);
+            return AVERROR_EXTERNAL;
+        }
+        if (s->zstream.avail_out == 0) {
+            if (s->y < s->cur_h) {
+                handle_row(s);
+            }
+            s->zstream.avail_out = s->crow_size;
+            s->zstream.next_out  = s->crow_buf;
+        }
+        if (ret == Z_STREAM_END && s->zstream.avail_in > 0) {
+            av_log(s->avctx, AV_LOG_WARNING,
+                   "%d undecompressed bytes left in buffer\n", s->zstream.avail_in);
+            return 0;
+        }
+    }
+    return 0;
+}
+
+static int decode_frame_lscr(AVCodecContext *avctx,
+                             void *data, int *got_frame,
+                             AVPacket *avpkt)
+{
+    LSCRContext *const s = avctx->priv_data;
+    GetByteContext *gb = &s->gb;
+    AVFrame *frame = data;
+    int ret, nb_blocks, offset = 0;
+
+    if (avpkt->size < 2)
+        return AVERROR_INVALIDDATA;
+    if (avpkt->size == 2)
+        return 0;
+
+    bytestream2_init(gb, avpkt->data, avpkt->size);
+
+    if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
+        return ret;
+
+    nb_blocks = bytestream2_get_le16(gb);
+    if (bytestream2_get_bytes_left(gb) < 2 + nb_blocks * (12 + 8))
+        return AVERROR_INVALIDDATA;
+
+    if (s->last_picture->data[0]) {
+        ret = av_frame_copy(frame, s->last_picture);
+        if (ret < 0)
+            return ret;
+    }
+
+    for (int b = 0; b < nb_blocks; b++) {
+        int x, y, x2, y2, w, h, left;
+        uint32_t csize, size;
+
+        s->zstream.zalloc = ff_png_zalloc;
+        s->zstream.zfree  = ff_png_zfree;
+        s->zstream.opaque = NULL;
+
+        if ((ret = inflateInit(&s->zstream)) != Z_OK) {
+            av_log(avctx, AV_LOG_ERROR, "inflateInit returned error %d\n", ret);
+            ret = AVERROR_EXTERNAL;
+            goto end;
+        }
+
+        bytestream2_seek(gb, 2 + b * 12, SEEK_SET);
+
+        x = bytestream2_get_le16(gb);
+        y = bytestream2_get_le16(gb);
+        x2 = bytestream2_get_le16(gb);
+        y2 = bytestream2_get_le16(gb);
+        w = x2-x;
+        s->cur_h = h = y2-y;
+
+        if (w <= 0 || x < 0 || x >= avctx->width || w + x > avctx->width ||
+            h <= 0 || y < 0 || y >= avctx->height || h + y > avctx->height) {
+            ret = AVERROR_INVALIDDATA;
+            goto end;
+        }
+
+        size = bytestream2_get_le32(gb);
+
+        frame->key_frame = (nb_blocks == 1) &&
+                           (w == avctx->width) &&
+                           (h == avctx->height) &&
+                           (x == 0) && (y == 0);
+
+        bytestream2_seek(gb, 2 + nb_blocks * 12 + offset, SEEK_SET);
+        csize = bytestream2_get_be32(gb);
+        if (bytestream2_get_le32(gb) != MKTAG('I', 'D', 'A', 'T')) {
+            ret = AVERROR_INVALIDDATA;
+            goto end;
+        }
+
+        offset += size;
+        left = size;
+
+        s->y                 = 0;
+        s->row_size          = w * 3;
+
+        av_fast_padded_malloc(&s->buffer, &s->buffer_size, s->row_size + 16);
+        if (!s->buffer) {
+            ret = AVERROR(ENOMEM);
+            goto end;
+        }
+
+        av_fast_padded_malloc(&s->last_row, &s->last_row_size, s->row_size);
+        if (!s->last_row) {
+            ret = AVERROR(ENOMEM);
+            goto end;
+        }
+
+        s->crow_size         = w * 3 + 1;
+        s->crow_buf          = s->buffer + 15;
+        s->zstream.avail_out = s->crow_size;
+        s->zstream.next_out  = s->crow_buf;
+        s->image_buf         = frame->data[0] + (avctx->height - y - 1) * frame->linesize[0] + x * 3;
+        s->image_linesize    =-frame->linesize[0];
+
+        while (left > 16) {
+            ret = decode_idat(s, csize);
+            if (ret < 0)
+                goto end;
+            left -= csize + 16;
+            if (left > 16) {
+                bytestream2_skip(gb, 4);
+                csize = bytestream2_get_be32(gb);
+                if (bytestream2_get_le32(gb) != MKTAG('I', 'D', 'A', 'T')) {
+                    ret = AVERROR_INVALIDDATA;
+                    goto end;
+                }
+            }
+        }
+
+        inflateEnd(&s->zstream);
+    }
+
+    frame->pict_type = frame->key_frame ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;
+
+    av_frame_unref(s->last_picture);
+    if ((ret = av_frame_ref(s->last_picture, frame)) < 0)
+        return ret;
+
+    *got_frame = 1;
+end:
+    inflateEnd(&s->zstream);
+
+    if (ret < 0)
+        return ret;
+    return avpkt->size;
+}
+
+static int lscr_decode_close(AVCodecContext *avctx)
+{
+    LSCRContext *s = avctx->priv_data;
+
+    av_frame_free(&s->last_picture);
+    av_freep(&s->buffer);
+    av_freep(&s->last_row);
+
+    return 0;
+}
+
+static int lscr_decode_init(AVCodecContext *avctx)
+{
+    LSCRContext *s = avctx->priv_data;
+
+    avctx->color_range = AVCOL_RANGE_JPEG;
+    avctx->pix_fmt     = AV_PIX_FMT_BGR24;
+
+    s->avctx = avctx;
+    s->last_picture = av_frame_alloc();
+    if (!s->last_picture)
+        return AVERROR(ENOMEM);
+
+    ff_pngdsp_init(&s->dsp);
+
+    return 0;
+}
+
+static void lscr_decode_flush(AVCodecContext *avctx)
+{
+    LSCRContext *s = avctx->priv_data;
+    av_frame_unref(s->last_picture);
+}
+
+AVCodec ff_lscr_decoder = {
+    .name           = "lscr",
+    .long_name      = NULL_IF_CONFIG_SMALL("LEAD Screen Capture"),
+    .type           = AVMEDIA_TYPE_VIDEO,
+    .id             = AV_CODEC_ID_LSCR,
+    .priv_data_size = sizeof(LSCRContext),
+    .init           = lscr_decode_init,
+    .close          = lscr_decode_close,
+    .decode         = decode_frame_lscr,
+    .flush          = lscr_decode_flush,
+    .capabilities   = AV_CODEC_CAP_DR1,
+    .caps_internal  = FF_CODEC_CAP_SKIP_FRAME_FILL_PARAM | FF_CODEC_CAP_INIT_THREADSAFE |
+                      FF_CODEC_CAP_ALLOCATE_PROGRESS,
+};
diff --git a/libavcodec/png.h b/libavcodec/png.h
index e967fcf38f..a15560131f 100644
--- a/libavcodec/png.h
+++ b/libavcodec/png.h
@@ -24,6 +24,8 @@
 
 #include <stdint.h>
 
+#include "pngdsp.h"
+
 #define PNG_COLOR_MASK_PALETTE    1
 #define PNG_COLOR_MASK_COLOR      2
 #define PNG_COLOR_MASK_ALPHA      4
@@ -61,4 +63,7 @@ int ff_png_pass_row_size(int pass, int bits_per_pixel, int width);
 
 void ff_add_png_paeth_prediction(uint8_t *dst, uint8_t *src, uint8_t *top, int w, int bpp);
 
+void ff_png_filter_row(PNGDSPContext *dsp, uint8_t *dst, int filter_type,
+                       uint8_t *src, uint8_t *last, int size, int bpp);
+
 #endif /* AVCODEC_PNG_H */
diff --git a/libavcodec/pngdec.c b/libavcodec/pngdec.c
index 61642b7cbe..e05e44f564 100644
--- a/libavcodec/pngdec.c
+++ b/libavcodec/pngdec.c
@@ -250,8 +250,8 @@ void ff_add_png_paeth_prediction(uint8_t *dst, uint8_t *src, uint8_t *top,
     }
 
 /* NOTE: 'dst' can be equal to 'last' */
-static void png_filter_row(PNGDSPContext *dsp, uint8_t *dst, int filter_type,
-                           uint8_t *src, uint8_t *last, int size, int bpp)
+void ff_png_filter_row(PNGDSPContext *dsp, uint8_t *dst, int filter_type,
+                       uint8_t *src, uint8_t *last, int size, int bpp)
 {
     int i, p, r, g, b, a;
 
@@ -343,8 +343,8 @@ static void png_handle_row(PNGDecContext *s)
         else
             last_row = ptr - s->image_linesize;
 
-        png_filter_row(&s->dsp, ptr, s->crow_buf[0], s->crow_buf + 1,
-                       last_row, s->row_size, s->bpp);
+        ff_png_filter_row(&s->dsp, ptr, s->crow_buf[0], s->crow_buf + 1,
+                          last_row, s->row_size, s->bpp);
         /* loco lags by 1 row so that it doesn't interfere with top prediction */
         if (s->filter_type == PNG_FILTER_TYPE_LOCO && s->y > 0) {
             if (s->bit_depth == 16) {
@@ -377,8 +377,8 @@ static void png_handle_row(PNGDecContext *s)
                  * wait for the next one */
                 if (got_line)
                     break;
-                png_filter_row(&s->dsp, s->tmp_row, s->crow_buf[0], s->crow_buf + 1,
-                               s->last_row, s->pass_row_size, s->bpp);
+                ff_png_filter_row(&s->dsp, s->tmp_row, s->crow_buf[0], s->crow_buf + 1,
+                                  s->last_row, s->pass_row_size, s->bpp);
                 FFSWAP(uint8_t *, s->last_row, s->tmp_row);
                 FFSWAP(unsigned int, s->last_row_size, s->tmp_row_size);
                 got_line = 1;
@@ -1585,148 +1585,6 @@ end:
 }
 #endif
 
-#if CONFIG_LSCR_DECODER
-static int decode_frame_lscr(AVCodecContext *avctx,
-                             void *data, int *got_frame,
-                             AVPacket *avpkt)
-{
-    PNGDecContext *const s = avctx->priv_data;
-    GetByteContext *gb = &s->gb;
-    AVFrame *frame = data;
-    int ret, nb_blocks, offset = 0;
-
-    if (avpkt->size < 2)
-        return AVERROR_INVALIDDATA;
-    if (avpkt->size == 2)
-        return 0;
-
-    bytestream2_init(gb, avpkt->data, avpkt->size);
-
-    if ((ret = ff_get_buffer(avctx, frame, AV_GET_BUFFER_FLAG_REF)) < 0)
-        return ret;
-
-    nb_blocks = bytestream2_get_le16(gb);
-    if (bytestream2_get_bytes_left(gb) < 2 + nb_blocks * (12 + 8))
-        return AVERROR_INVALIDDATA;
-
-    if (s->last_picture.f->data[0]) {
-        ret = av_frame_copy(frame, s->last_picture.f);
-        if (ret < 0)
-            return ret;
-    }
-
-    for (int b = 0; b < nb_blocks; b++) {
-        int x, y, x2, y2, w, h, left;
-        uint32_t csize, size;
-
-        s->zstream.zalloc = ff_png_zalloc;
-        s->zstream.zfree  = ff_png_zfree;
-        s->zstream.opaque = NULL;
-
-        if ((ret = inflateInit(&s->zstream)) != Z_OK) {
-            av_log(avctx, AV_LOG_ERROR, "inflateInit returned error %d\n", ret);
-            ret = AVERROR_EXTERNAL;
-            goto end;
-        }
-
-        bytestream2_seek(gb, 2 + b * 12, SEEK_SET);
-
-        x = bytestream2_get_le16(gb);
-        y = bytestream2_get_le16(gb);
-        x2 = bytestream2_get_le16(gb);
-        y2 = bytestream2_get_le16(gb);
-        s->width  = s->cur_w = w = x2-x;
-        s->height = s->cur_h = h = y2-y;
-
-        if (w <= 0 || x < 0 || x >= avctx->width || w + x > avctx->width ||
-            h <= 0 || y < 0 || y >= avctx->height || h + y > avctx->height) {
-            ret = AVERROR_INVALIDDATA;
-            goto end;
-        }
-
-        size = bytestream2_get_le32(gb);
-
-        frame->key_frame = (nb_blocks == 1) &&
-                           (w == avctx->width) &&
-                           (h == avctx->height) &&
-                           (x == 0) && (y == 0);
-
-        bytestream2_seek(gb, 2 + nb_blocks * 12 + offset, SEEK_SET);
-        csize = bytestream2_get_be32(gb);
-        if (bytestream2_get_le32(gb) != MKTAG('I', 'D', 'A', 'T')) {
-            ret = AVERROR_INVALIDDATA;
-            goto end;
-        }
-
-        offset += size;
-        left = size;
-
-        s->y                 = 0;
-        s->row_size          = w * 3;
-
-        av_fast_padded_malloc(&s->buffer, &s->buffer_size, s->row_size + 16);
-        if (!s->buffer) {
-            ret = AVERROR(ENOMEM);
-            goto end;
-        }
-
-        av_fast_padded_malloc(&s->last_row, &s->last_row_size, s->row_size);
-        if (!s->last_row) {
-            ret = AVERROR(ENOMEM);
-            goto end;
-        }
-
-        s->crow_size         = w * 3 + 1;
-        s->crow_buf          = s->buffer + 15;
-        s->zstream.avail_out = s->crow_size;
-        s->zstream.next_out  = s->crow_buf;
-        s->image_buf         = frame->data[0] + (avctx->height - y - 1) * frame->linesize[0] + x * 3;
-        s->image_linesize    =-frame->linesize[0];
-        s->bpp               = 3;
-        s->pic_state         = 0;
-
-        while (left > 16) {
-            ret = png_decode_idat(s, csize);
-            if (ret < 0)
-                goto end;
-            left -= csize + 16;
-            if (left > 16) {
-                bytestream2_skip(gb, 4);
-                csize = bytestream2_get_be32(gb);
-                if (bytestream2_get_le32(gb) != MKTAG('I', 'D', 'A', 'T')) {
-                    ret = AVERROR_INVALIDDATA;
-                    goto end;
-                }
-            }
-        }
-
-        inflateEnd(&s->zstream);
-    }
-
-    frame->pict_type = frame->key_frame ? AV_PICTURE_TYPE_I : AV_PICTURE_TYPE_P;
-
-    av_frame_unref(s->last_picture.f);
-    if ((ret = av_frame_ref(s->last_picture.f, frame)) < 0)
-        return ret;
-
-    *got_frame = 1;
-end:
-    inflateEnd(&s->zstream);
-
-    if (ret < 0)
-        return ret;
-    return avpkt->size;
-}
-
-static void decode_flush(AVCodecContext *avctx)
-{
-    PNGDecContext *s = avctx->priv_data;
-
-    av_frame_unref(s->last_picture.f);
-}
-
-#endif
-
 #if HAVE_THREADS
 static int update_thread_context(AVCodecContext *dst, const AVCodecContext *src)
 {
@@ -1783,9 +1641,6 @@ static av_cold int png_dec_init(AVCodecContext *avctx)
 
     avctx->color_range = AVCOL_RANGE_JPEG;
 
-    if (avctx->codec_id == AV_CODEC_ID_LSCR)
-        avctx->pix_fmt = AV_PIX_FMT_BGR24;
-
     s->avctx = avctx;
     s->previous_picture.f = av_frame_alloc();
     s->last_picture.f = av_frame_alloc();
@@ -1855,20 +1710,3 @@ AVCodec ff_png_decoder = {
                       FF_CODEC_CAP_ALLOCATE_PROGRESS,
 };
 #endif
-
-#if CONFIG_LSCR_DECODER
-AVCodec ff_lscr_decoder = {
-    .name           = "lscr",
-    .long_name      = NULL_IF_CONFIG_SMALL("LEAD Screen Capture"),
-    .type           = AVMEDIA_TYPE_VIDEO,
-    .id             = AV_CODEC_ID_LSCR,
-    .priv_data_size = sizeof(PNGDecContext),
-    .init           = png_dec_init,
-    .close          = png_dec_end,
-    .decode         = decode_frame_lscr,
-    .flush          = decode_flush,
-    .capabilities   = AV_CODEC_CAP_DR1 /*| AV_CODEC_CAP_DRAW_HORIZ_BAND*/,
-    .caps_internal  = FF_CODEC_CAP_SKIP_FRAME_FILL_PARAM | FF_CODEC_CAP_INIT_THREADSAFE |
-                      FF_CODEC_CAP_ALLOCATE_PROGRESS,
-};
-#endif