mjpeg: Split off bits shared by MJPEG and LJPEG encoders

This obviates a dependency of the LJPEG encoder on mpegvideo.

7 files changed, 360 insertions, 294 deletions

diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index 1881b0b963..bfe50f352e 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -233,7 +233,7 @@ OBJS-$(CONFIG_JV_DECODER)              += jvdec.o
 OBJS-$(CONFIG_KGV1_DECODER)            += kgv1dec.o
 OBJS-$(CONFIG_KMVC_DECODER)            += kmvc.o
 OBJS-$(CONFIG_LAGARITH_DECODER)        += lagarith.o lagarithrac.o
-OBJS-$(CONFIG_LJPEG_ENCODER)           += ljpegenc.o mjpegenc.o mjpeg.o
+OBJS-$(CONFIG_LJPEG_ENCODER)           += ljpegenc.o mjpeg.o mjpegenc_common.o
 OBJS-$(CONFIG_LOCO_DECODER)            += loco.o
 OBJS-$(CONFIG_MACE3_DECODER)           += mace.o
 OBJS-$(CONFIG_MACE6_DECODER)           += mace.o
@@ -242,7 +242,7 @@ OBJS-$(CONFIG_METASOUND_DECODER)       += metasound.o metasound_data.o \
                                           twinvq.o
 OBJS-$(CONFIG_MIMIC_DECODER)           += mimic.o
 OBJS-$(CONFIG_MJPEG_DECODER)           += mjpegdec.o mjpeg.o
-OBJS-$(CONFIG_MJPEG_ENCODER)           += mjpegenc.o mjpeg.o
+OBJS-$(CONFIG_MJPEG_ENCODER)           += mjpegenc.o mjpeg.o mjpegenc_common.o
 OBJS-$(CONFIG_MJPEGB_DECODER)          += mjpegbdec.o
 OBJS-$(CONFIG_MLP_DECODER)             += mlpdec.o mlpdsp.o
 OBJS-$(CONFIG_MMVIDEO_DECODER)         += mmvideo.o
diff --git a/libavcodec/ljpegenc.c b/libavcodec/ljpegenc.c
index e111c8c557..9f06818667 100644
--- a/libavcodec/ljpegenc.c
+++ b/libavcodec/ljpegenc.c
@@ -37,6 +37,7 @@
 #include "avcodec.h"
 #include "dsputil.h"
 #include "internal.h"
+#include "mjpegenc_common.h"
 #include "mpegvideo.h"
 #include "mjpeg.h"
 #include "mjpegenc.h"
diff --git a/libavcodec/mjpegenc.c b/libavcodec/mjpegenc.c
index 30433c3ff6..9ce07def8f 100644
--- a/libavcodec/mjpegenc.c
+++ b/libavcodec/mjpegenc.c
@@ -35,6 +35,7 @@
 #include "libavutil/pixdesc.h"
 
 #include "avcodec.h"
+#include "mjpegenc_common.h"
 #include "mpegvideo.h"
 #include "mjpeg.h"
 #include "mjpegenc.h"
@@ -77,291 +78,6 @@ void ff_mjpeg_encode_close(MpegEncContext *s)
     av_free(s->mjpeg_ctx);
 }
 
-/* table_class: 0 = DC coef, 1 = AC coefs */
-static int put_huffman_table(PutBitContext *p, int table_class, int table_id,
-                             const uint8_t *bits_table, const uint8_t *value_table)
-{
-    int n, i;
-
-    put_bits(p, 4, table_class);
-    put_bits(p, 4, table_id);
-
-    n = 0;
-    for(i=1;i<=16;i++) {
-        n += bits_table[i];
-        put_bits(p, 8, bits_table[i]);
-    }
-
-    for(i=0;i<n;i++)
-        put_bits(p, 8, value_table[i]);
-
-    return n + 17;
-}
-
-static void jpeg_table_header(PutBitContext *p, ScanTable *intra_scantable,
-                              uint16_t intra_matrix[64])
-{
-    int i, j, size;
-    uint8_t *ptr;
-
-    /* quant matrixes */
-    put_marker(p, DQT);
-    put_bits(p, 16, 2 + 1 * (1 + 64));
-    put_bits(p, 4, 0); /* 8 bit precision */
-    put_bits(p, 4, 0); /* table 0 */
-    for(i=0;i<64;i++) {
-        j = intra_scantable->permutated[i];
-        put_bits(p, 8, intra_matrix[j]);
-    }
-
-    /* huffman table */
-    put_marker(p, DHT);
-    flush_put_bits(p);
-    ptr = put_bits_ptr(p);
-    put_bits(p, 16, 0); /* patched later */
-    size = 2;
-    size += put_huffman_table(p, 0, 0, avpriv_mjpeg_bits_dc_luminance,
-                              avpriv_mjpeg_val_dc);
-    size += put_huffman_table(p, 0, 1, avpriv_mjpeg_bits_dc_chrominance,
-                              avpriv_mjpeg_val_dc);
-
-    size += put_huffman_table(p, 1, 0, avpriv_mjpeg_bits_ac_luminance,
-                              avpriv_mjpeg_val_ac_luminance);
-    size += put_huffman_table(p, 1, 1, avpriv_mjpeg_bits_ac_chrominance,
-                              avpriv_mjpeg_val_ac_chrominance);
-    AV_WB16(ptr, size);
-}
-
-static void jpeg_put_comments(AVCodecContext *avctx, PutBitContext *p)
-{
-    int size;
-    uint8_t *ptr;
-
-    if (avctx->sample_aspect_ratio.num > 0 && avctx->sample_aspect_ratio.den > 0) {
-        /* JFIF header */
-        put_marker(p, APP0);
-        put_bits(p, 16, 16);
-        avpriv_put_string(p, "JFIF", 1); /* this puts the trailing zero-byte too */
-        put_bits(p, 16, 0x0201);         /* v 1.02 */
-        put_bits(p,  8, 0);              /* units type: 0 - aspect ratio */
-        put_bits(p, 16, avctx->sample_aspect_ratio.num);
-        put_bits(p, 16, avctx->sample_aspect_ratio.den);
-        put_bits(p, 8, 0); /* thumbnail width */
-        put_bits(p, 8, 0); /* thumbnail height */
-    }
-
-    /* comment */
-    if (!(avctx->flags & CODEC_FLAG_BITEXACT)) {
-        put_marker(p, COM);
-        flush_put_bits(p);
-        ptr = put_bits_ptr(p);
-        put_bits(p, 16, 0); /* patched later */
-        avpriv_put_string(p, LIBAVCODEC_IDENT, 1);
-        size = strlen(LIBAVCODEC_IDENT)+3;
-        AV_WB16(ptr, size);
-    }
-
-    if (avctx->pix_fmt == AV_PIX_FMT_YUV420P ||
-        avctx->pix_fmt == AV_PIX_FMT_YUV422P ||
-        avctx->pix_fmt == AV_PIX_FMT_YUV444P) {
-        put_marker(p, COM);
-        flush_put_bits(p);
-        ptr = put_bits_ptr(p);
-        put_bits(p, 16, 0); /* patched later */
-        avpriv_put_string(p, "CS=ITU601", 1);
-        size = strlen("CS=ITU601")+3;
-        AV_WB16(ptr, size);
-    }
-}
-
-void ff_mjpeg_encode_picture_header(AVCodecContext *avctx, PutBitContext *pb,
-                                    ScanTable *intra_scantable,
-                                    uint16_t intra_matrix[64])
-{
-    int chroma_h_shift, chroma_v_shift;
-    const int lossless = avctx->codec_id != AV_CODEC_ID_MJPEG;
-    int hsample[3], vsample[3];
-
-    av_pix_fmt_get_chroma_sub_sample(avctx->pix_fmt, &chroma_h_shift,
-                                     &chroma_v_shift);
-
-    if (avctx->codec->id == AV_CODEC_ID_LJPEG &&
-        avctx->pix_fmt   == AV_PIX_FMT_BGR24) {
-        vsample[0] = hsample[0] =
-        vsample[1] = hsample[1] =
-        vsample[2] = hsample[2] = 1;
-    } else {
-        vsample[0] = 2;
-        vsample[1] = 2 >> chroma_v_shift;
-        vsample[2] = 2 >> chroma_v_shift;
-        hsample[0] = 2;
-        hsample[1] = 2 >> chroma_h_shift;
-        hsample[2] = 2 >> chroma_h_shift;
-    }
-
-    put_marker(pb, SOI);
-
-    jpeg_put_comments(avctx, pb);
-
-    jpeg_table_header(pb, intra_scantable, intra_matrix);
-
-    switch (avctx->codec_id) {
-    case AV_CODEC_ID_MJPEG:  put_marker(pb, SOF0 ); break;
-    case AV_CODEC_ID_LJPEG:  put_marker(pb, SOF3 ); break;
-    default: assert(0);
-    }
-
-    put_bits(pb, 16, 17);
-    if (lossless && avctx->pix_fmt == AV_PIX_FMT_BGR24)
-        put_bits(pb, 8, 9); /* 9 bits/component RCT */
-    else
-        put_bits(pb, 8, 8); /* 8 bits/component */
-    put_bits(pb, 16, avctx->height);
-    put_bits(pb, 16, avctx->width);
-    put_bits(pb, 8, 3); /* 3 components */
-
-    /* Y component */
-    put_bits(pb, 8, 1); /* component number */
-    put_bits(pb, 4, hsample[0]); /* H factor */
-    put_bits(pb, 4, vsample[0]); /* V factor */
-    put_bits(pb, 8, 0); /* select matrix */
-
-    /* Cb component */
-    put_bits(pb, 8, 2); /* component number */
-    put_bits(pb, 4, hsample[1]); /* H factor */
-    put_bits(pb, 4, vsample[1]); /* V factor */
-    put_bits(pb, 8, 0); /* select matrix */
-
-    /* Cr component */
-    put_bits(pb, 8, 3); /* component number */
-    put_bits(pb, 4, hsample[2]); /* H factor */
-    put_bits(pb, 4, vsample[2]); /* V factor */
-    put_bits(pb, 8, 0); /* select matrix */
-
-    /* scan header */
-    put_marker(pb, SOS);
-    put_bits(pb, 16, 12); /* length */
-    put_bits(pb, 8, 3); /* 3 components */
-
-    /* Y component */
-    put_bits(pb, 8, 1); /* index */
-    put_bits(pb, 4, 0); /* DC huffman table index */
-    put_bits(pb, 4, 0); /* AC huffman table index */
-
-    /* Cb component */
-    put_bits(pb, 8, 2); /* index */
-    put_bits(pb, 4, 1); /* DC huffman table index */
-    put_bits(pb, 4, lossless ? 0 : 1); /* AC huffman table index */
-
-    /* Cr component */
-    put_bits(pb, 8, 3); /* index */
-    put_bits(pb, 4, 1); /* DC huffman table index */
-    put_bits(pb, 4, lossless ? 0 : 1); /* AC huffman table index */
-
-    put_bits(pb, 8, lossless ? avctx->prediction_method + 1 : 0); /* Ss (not used) */
-
-    switch (avctx->codec_id) {
-    case AV_CODEC_ID_MJPEG:  put_bits(pb, 8, 63); break; /* Se (not used) */
-    case AV_CODEC_ID_LJPEG:  put_bits(pb, 8,  0); break; /* not used */
-    default: assert(0);
-    }
-
-    put_bits(pb, 8, 0); /* Ah/Al (not used) */
-}
-
-static void escape_FF(PutBitContext *pb, int start)
-{
-    int size = put_bits_count(pb) - start * 8;
-    int i, ff_count;
-    uint8_t *buf = pb->buf + start;
-    int align= (-(size_t)(buf))&3;
-
-    assert((size&7) == 0);
-    size >>= 3;
-
-    ff_count=0;
-    for(i=0; i<size && i<align; i++){
-        if(buf[i]==0xFF) ff_count++;
-    }
-    for(; i<size-15; i+=16){
-        int acc, v;
-
-        v= *(uint32_t*)(&buf[i]);
-        acc= (((v & (v>>4))&0x0F0F0F0F)+0x01010101)&0x10101010;
-        v= *(uint32_t*)(&buf[i+4]);
-        acc+=(((v & (v>>4))&0x0F0F0F0F)+0x01010101)&0x10101010;
-        v= *(uint32_t*)(&buf[i+8]);
-        acc+=(((v & (v>>4))&0x0F0F0F0F)+0x01010101)&0x10101010;
-        v= *(uint32_t*)(&buf[i+12]);
-        acc+=(((v & (v>>4))&0x0F0F0F0F)+0x01010101)&0x10101010;
-
-        acc>>=4;
-        acc+= (acc>>16);
-        acc+= (acc>>8);
-        ff_count+= acc&0xFF;
-    }
-    for(; i<size; i++){
-        if(buf[i]==0xFF) ff_count++;
-    }
-
-    if(ff_count==0) return;
-
-    flush_put_bits(pb);
-    skip_put_bytes(pb, ff_count);
-
-    for(i=size-1; ff_count; i--){
-        int v= buf[i];
-
-        if(v==0xFF){
-            buf[i+ff_count]= 0;
-            ff_count--;
-        }
-
-        buf[i+ff_count]= v;
-    }
-}
-
-void ff_mjpeg_encode_stuffing(PutBitContext * pbc)
-{
-    int length;
-    length= (-put_bits_count(pbc))&7;
-    if(length) put_bits(pbc, length, (1<<length)-1);
-}
-
-void ff_mjpeg_encode_picture_trailer(PutBitContext *pb, int header_bits)
-{
-    ff_mjpeg_encode_stuffing(pb);
-    flush_put_bits(pb);
-
-    assert((header_bits & 7) == 0);
-
-    escape_FF(pb, header_bits >> 3);
-
-    put_marker(pb, EOI);
-}
-
-void ff_mjpeg_encode_dc(PutBitContext *pb, int val,
-                        uint8_t *huff_size, uint16_t *huff_code)
-{
-    int mant, nbits;
-
-    if (val == 0) {
-        put_bits(pb, huff_size[0], huff_code[0]);
-    } else {
-        mant = val;
-        if (val < 0) {
-            val = -val;
-            mant--;
-        }
-
-        nbits= av_log2_16bit(val) + 1;
-
-        put_bits(pb, huff_size[nbits], huff_code[nbits]);
-
-        put_sbits(pb, nbits, mant);
-    }
-}
-
 static void encode_block(MpegEncContext *s, int16_t *block, int n)
 {
     int mant, nbits, code, i, j;
diff --git a/libavcodec/mjpegenc.h b/libavcodec/mjpegenc.h
index 2ad55f29f0..6054db1113 100644
--- a/libavcodec/mjpegenc.h
+++ b/libavcodec/mjpegenc.h
@@ -51,13 +51,6 @@ typedef struct MJpegContext {
 
 int  ff_mjpeg_encode_init(MpegEncContext *s);
 void ff_mjpeg_encode_close(MpegEncContext *s);
-void ff_mjpeg_encode_picture_header(AVCodecContext *avctx, PutBitContext *pb,
-                                    ScanTable *intra_scantable,
-                                    uint16_t intra_matrix[64]);
-void ff_mjpeg_encode_picture_trailer(PutBitContext *pb, int header_bits);
-void ff_mjpeg_encode_stuffing(PutBitContext *pbc);
-void ff_mjpeg_encode_dc(PutBitContext *pb, int val,
-                        uint8_t *huff_size, uint16_t *huff_code);
 void ff_mjpeg_encode_mb(MpegEncContext *s, int16_t block[6][64]);
 
 #endif /* AVCODEC_MJPEGENC_H */
diff --git a/libavcodec/mjpegenc_common.c b/libavcodec/mjpegenc_common.c
new file mode 100644
index 0000000000..3dba414f1d
--- /dev/null
+++ b/libavcodec/mjpegenc_common.c
@@ -0,0 +1,317 @@
+/*
+ * lossless JPEG shared bits
+ *
+ * This file is part of Libav.
+ *
+ * Libav 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.
+ *
+ * Libav 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 Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <stdint.h>
+#include <string.h>
+
+#include "libavutil/common.h"
+#include "libavutil/pixdesc.h"
+#include "libavutil/pixfmt.h"
+
+#include "avcodec.h"
+#include "dsputil.h"
+#include "put_bits.h"
+#include "mjpegenc_common.h"
+#include "mjpeg.h"
+
+/* table_class: 0 = DC coef, 1 = AC coefs */
+static int put_huffman_table(PutBitContext *p, int table_class, int table_id,
+                             const uint8_t *bits_table, const uint8_t *value_table)
+{
+    int n, i;
+
+    put_bits(p, 4, table_class);
+    put_bits(p, 4, table_id);
+
+    n = 0;
+    for(i=1;i<=16;i++) {
+        n += bits_table[i];
+        put_bits(p, 8, bits_table[i]);
+    }
+
+    for(i=0;i<n;i++)
+        put_bits(p, 8, value_table[i]);
+
+    return n + 17;
+}
+
+static void jpeg_table_header(PutBitContext *p, ScanTable *intra_scantable,
+                              uint16_t intra_matrix[64])
+{
+    int i, j, size;
+    uint8_t *ptr;
+
+    /* quant matrixes */
+    put_marker(p, DQT);
+    put_bits(p, 16, 2 + 1 * (1 + 64));
+    put_bits(p, 4, 0); /* 8 bit precision */
+    put_bits(p, 4, 0); /* table 0 */
+    for(i=0;i<64;i++) {
+        j = intra_scantable->permutated[i];
+        put_bits(p, 8, intra_matrix[j]);
+    }
+
+    /* huffman table */
+    put_marker(p, DHT);
+    flush_put_bits(p);
+    ptr = put_bits_ptr(p);
+    put_bits(p, 16, 0); /* patched later */
+    size = 2;
+    size += put_huffman_table(p, 0, 0, avpriv_mjpeg_bits_dc_luminance,
+                              avpriv_mjpeg_val_dc);
+    size += put_huffman_table(p, 0, 1, avpriv_mjpeg_bits_dc_chrominance,
+                              avpriv_mjpeg_val_dc);
+
+    size += put_huffman_table(p, 1, 0, avpriv_mjpeg_bits_ac_luminance,
+                              avpriv_mjpeg_val_ac_luminance);
+    size += put_huffman_table(p, 1, 1, avpriv_mjpeg_bits_ac_chrominance,
+                              avpriv_mjpeg_val_ac_chrominance);
+    AV_WB16(ptr, size);
+}
+
+static void jpeg_put_comments(AVCodecContext *avctx, PutBitContext *p)
+{
+    int size;
+    uint8_t *ptr;
+
+    if (avctx->sample_aspect_ratio.num > 0 && avctx->sample_aspect_ratio.den > 0) {
+        /* JFIF header */
+        put_marker(p, APP0);
+        put_bits(p, 16, 16);
+        avpriv_put_string(p, "JFIF", 1); /* this puts the trailing zero-byte too */
+        put_bits(p, 16, 0x0201);         /* v 1.02 */
+        put_bits(p,  8, 0);              /* units type: 0 - aspect ratio */
+        put_bits(p, 16, avctx->sample_aspect_ratio.num);
+        put_bits(p, 16, avctx->sample_aspect_ratio.den);
+        put_bits(p, 8, 0); /* thumbnail width */
+        put_bits(p, 8, 0); /* thumbnail height */
+    }
+
+    /* comment */
+    if (!(avctx->flags & CODEC_FLAG_BITEXACT)) {
+        put_marker(p, COM);
+        flush_put_bits(p);
+        ptr = put_bits_ptr(p);
+        put_bits(p, 16, 0); /* patched later */
+        avpriv_put_string(p, LIBAVCODEC_IDENT, 1);
+        size = strlen(LIBAVCODEC_IDENT)+3;
+        AV_WB16(ptr, size);
+    }
+
+    if (avctx->pix_fmt == AV_PIX_FMT_YUV420P ||
+        avctx->pix_fmt == AV_PIX_FMT_YUV422P ||
+        avctx->pix_fmt == AV_PIX_FMT_YUV444P) {
+        put_marker(p, COM);
+        flush_put_bits(p);
+        ptr = put_bits_ptr(p);
+        put_bits(p, 16, 0); /* patched later */
+        avpriv_put_string(p, "CS=ITU601", 1);
+        size = strlen("CS=ITU601")+3;
+        AV_WB16(ptr, size);
+    }
+}
+
+void ff_mjpeg_encode_picture_header(AVCodecContext *avctx, PutBitContext *pb,
+                                    ScanTable *intra_scantable,
+                                    uint16_t intra_matrix[64])
+{
+    int chroma_h_shift, chroma_v_shift;
+    const int lossless = avctx->codec_id != AV_CODEC_ID_MJPEG;
+    int hsample[3], vsample[3];
+
+    av_pix_fmt_get_chroma_sub_sample(avctx->pix_fmt, &chroma_h_shift,
+                                     &chroma_v_shift);
+
+    if (avctx->codec->id == AV_CODEC_ID_LJPEG &&
+        avctx->pix_fmt   == AV_PIX_FMT_BGR24) {
+        vsample[0] = hsample[0] =
+        vsample[1] = hsample[1] =
+        vsample[2] = hsample[2] = 1;
+    } else {
+        vsample[0] = 2;
+        vsample[1] = 2 >> chroma_v_shift;
+        vsample[2] = 2 >> chroma_v_shift;
+        hsample[0] = 2;
+        hsample[1] = 2 >> chroma_h_shift;
+        hsample[2] = 2 >> chroma_h_shift;
+    }
+
+    put_marker(pb, SOI);
+
+    jpeg_put_comments(avctx, pb);
+
+    jpeg_table_header(pb, intra_scantable, intra_matrix);
+
+    switch (avctx->codec_id) {
+    case AV_CODEC_ID_MJPEG:  put_marker(pb, SOF0 ); break;
+    case AV_CODEC_ID_LJPEG:  put_marker(pb, SOF3 ); break;
+    default: assert(0);
+    }
+
+    put_bits(pb, 16, 17);
+    if (lossless && avctx->pix_fmt == AV_PIX_FMT_BGR24)
+        put_bits(pb, 8, 9); /* 9 bits/component RCT */
+    else
+        put_bits(pb, 8, 8); /* 8 bits/component */
+    put_bits(pb, 16, avctx->height);
+    put_bits(pb, 16, avctx->width);
+    put_bits(pb, 8, 3); /* 3 components */
+
+    /* Y component */
+    put_bits(pb, 8, 1); /* component number */
+    put_bits(pb, 4, hsample[0]); /* H factor */
+    put_bits(pb, 4, vsample[0]); /* V factor */
+    put_bits(pb, 8, 0); /* select matrix */
+
+    /* Cb component */
+    put_bits(pb, 8, 2); /* component number */
+    put_bits(pb, 4, hsample[1]); /* H factor */
+    put_bits(pb, 4, vsample[1]); /* V factor */
+    put_bits(pb, 8, 0); /* select matrix */
+
+    /* Cr component */
+    put_bits(pb, 8, 3); /* component number */
+    put_bits(pb, 4, hsample[2]); /* H factor */
+    put_bits(pb, 4, vsample[2]); /* V factor */
+    put_bits(pb, 8, 0); /* select matrix */
+
+    /* scan header */
+    put_marker(pb, SOS);
+    put_bits(pb, 16, 12); /* length */
+    put_bits(pb, 8, 3); /* 3 components */
+
+    /* Y component */
+    put_bits(pb, 8, 1); /* index */
+    put_bits(pb, 4, 0); /* DC huffman table index */
+    put_bits(pb, 4, 0); /* AC huffman table index */
+
+    /* Cb component */
+    put_bits(pb, 8, 2); /* index */
+    put_bits(pb, 4, 1); /* DC huffman table index */
+    put_bits(pb, 4, lossless ? 0 : 1); /* AC huffman table index */
+
+    /* Cr component */
+    put_bits(pb, 8, 3); /* index */
+    put_bits(pb, 4, 1); /* DC huffman table index */
+    put_bits(pb, 4, lossless ? 0 : 1); /* AC huffman table index */
+
+    put_bits(pb, 8, lossless ? avctx->prediction_method + 1 : 0); /* Ss (not used) */
+
+    switch (avctx->codec_id) {
+    case AV_CODEC_ID_MJPEG:  put_bits(pb, 8, 63); break; /* Se (not used) */
+    case AV_CODEC_ID_LJPEG:  put_bits(pb, 8,  0); break; /* not used */
+    default: assert(0);
+    }
+
+    put_bits(pb, 8, 0); /* Ah/Al (not used) */
+}
+
+static void escape_FF(PutBitContext *pb, int start)
+{
+    int size = put_bits_count(pb) - start * 8;
+    int i, ff_count;
+    uint8_t *buf = pb->buf + start;
+    int align= (-(size_t)(buf))&3;
+
+    assert((size&7) == 0);
+    size >>= 3;
+
+    ff_count=0;
+    for(i=0; i<size && i<align; i++){
+        if(buf[i]==0xFF) ff_count++;
+    }
+    for(; i<size-15; i+=16){
+        int acc, v;
+
+        v= *(uint32_t*)(&buf[i]);
+        acc= (((v & (v>>4))&0x0F0F0F0F)+0x01010101)&0x10101010;
+        v= *(uint32_t*)(&buf[i+4]);
+        acc+=(((v & (v>>4))&0x0F0F0F0F)+0x01010101)&0x10101010;
+        v= *(uint32_t*)(&buf[i+8]);
+        acc+=(((v & (v>>4))&0x0F0F0F0F)+0x01010101)&0x10101010;
+        v= *(uint32_t*)(&buf[i+12]);
+        acc+=(((v & (v>>4))&0x0F0F0F0F)+0x01010101)&0x10101010;
+
+        acc>>=4;
+        acc+= (acc>>16);
+        acc+= (acc>>8);
+        ff_count+= acc&0xFF;
+    }
+    for(; i<size; i++){
+        if(buf[i]==0xFF) ff_count++;
+    }
+
+    if(ff_count==0) return;
+
+    flush_put_bits(pb);
+    skip_put_bytes(pb, ff_count);
+
+    for(i=size-1; ff_count; i--){
+        int v= buf[i];
+
+        if(v==0xFF){
+            buf[i+ff_count]= 0;
+            ff_count--;
+        }
+
+        buf[i+ff_count]= v;
+    }
+}
+
+void ff_mjpeg_encode_stuffing(PutBitContext * pbc)
+{
+    int length;
+    length= (-put_bits_count(pbc))&7;
+    if(length) put_bits(pbc, length, (1<<length)-1);
+}
+
+void ff_mjpeg_encode_picture_trailer(PutBitContext *pb, int header_bits)
+{
+    ff_mjpeg_encode_stuffing(pb);
+    flush_put_bits(pb);
+
+    assert((header_bits & 7) == 0);
+
+    escape_FF(pb, header_bits >> 3);
+
+    put_marker(pb, EOI);
+}
+
+void ff_mjpeg_encode_dc(PutBitContext *pb, int val,
+                        uint8_t *huff_size, uint16_t *huff_code)
+{
+    int mant, nbits;
+
+    if (val == 0) {
+        put_bits(pb, huff_size[0], huff_code[0]);
+    } else {
+        mant = val;
+        if (val < 0) {
+            val = -val;
+            mant--;
+        }
+
+        nbits= av_log2_16bit(val) + 1;
+
+        put_bits(pb, huff_size[nbits], huff_code[nbits]);
+
+        put_sbits(pb, nbits, mant);
+    }
+}
diff --git a/libavcodec/mjpegenc_common.h b/libavcodec/mjpegenc_common.h
new file mode 100644
index 0000000000..57dc9ddb5b
--- /dev/null
+++ b/libavcodec/mjpegenc_common.h
@@ -0,0 +1,38 @@
+/*
+ * lossless JPEG shared bits
+ *
+ * This file is part of Libav.
+ *
+ * Libav 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.
+ *
+ * Libav 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 Libav; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVCODEC_MJPEGENC_COMMON_H
+#define AVCODEC_MJPEGENC_COMMON_H
+
+#include <stdint.h>
+
+#include "avcodec.h"
+#include "dsputil.h"
+#include "put_bits.h"
+
+void ff_mjpeg_encode_picture_header(AVCodecContext *avctx, PutBitContext *pb,
+                                    ScanTable *intra_scantable,
+                                    uint16_t intra_matrix[64]);
+void ff_mjpeg_encode_picture_trailer(PutBitContext *pb, int header_bits);
+void ff_mjpeg_encode_stuffing(PutBitContext *pbc);
+void ff_mjpeg_encode_dc(PutBitContext *pb, int val,
+                        uint8_t *huff_size, uint16_t *huff_code);
+
+#endif /* AVCODEC_MJPEGENC_COMMON_H */
diff --git a/libavcodec/mpegvideo_enc.c b/libavcodec/mpegvideo_enc.c
index 8985030d70..3baf37a5be 100644
--- a/libavcodec/mpegvideo_enc.c
+++ b/libavcodec/mpegvideo_enc.c
@@ -42,6 +42,7 @@
 #include "mpegvideo.h"
 #include "h261.h"
 #include "h263.h"
+#include "mjpegenc_common.h"
 #include "mathops.h"
 #include "mpegutils.h"
 #include "mjpegenc.h"