From 7866eeff46f3807696100d1061b6cd07af0dd9eb Mon Sep 17 00:00:00 2001
From: Michael Niedermayer <michaelni@gmx.at>
Date: Thu, 12 Sep 2002 11:10:33 +0000
Subject: [PATCH] m4v input support return the correct number of bytes consumed
 for decding h263 like formats (needed for reading raw streams) this could
 break some divx files with b frames, so please tell me ASAP if u notice any
 problems

Originally committed as revision 924 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
 libav/raw.c          | 27 +++++++++++++++++++++++----
 libavcodec/h263dec.c | 31 ++++++++++++++++++++++++-------
 2 files changed, 47 insertions(+), 11 deletions(-)

diff --git a/libav/raw.c b/libav/raw.c
index 47efe1af06..6cfa268e13 100644
--- a/libav/raw.c
+++ b/libav/raw.c
@@ -81,13 +81,19 @@ static int raw_read_header(AVFormatContext *s,
 int raw_read_packet(AVFormatContext *s,
                     AVPacket *pkt)
 {
-    int ret;
+    int ret, size;
+    AVStream *st = s->streams[0];
+    
+    if(st->codec.codec_id == CODEC_ID_MPEG4)
+        size= 1024*1024; //cant handle partial frames
+    else
+        size= RAW_PACKET_SIZE;
 
-    if (av_new_packet(pkt, RAW_PACKET_SIZE) < 0)
+    if (av_new_packet(pkt, size) < 0)
         return -EIO;
 
     pkt->stream_index = 0;
-    ret = get_buffer(&s->pb, pkt->data, RAW_PACKET_SIZE);
+    ret = get_buffer(&s->pb, pkt->data, size);
     if (ret <= 0) {
         av_free_packet(pkt);
         return -EIO;
@@ -132,7 +138,8 @@ static int video_read_header(AVFormatContext *s,
     st->codec.codec_type = CODEC_TYPE_VIDEO;
     st->codec.codec_id = s->iformat->value;
     /* for mjpeg, specify frame rate */
-    if (st->codec.codec_id == CODEC_ID_MJPEG) {
+    /* for mpeg4 specify it too (most mpeg4 streams dont have the fixed_vop_rate set ...)*/
+    if (st->codec.codec_id == CODEC_ID_MJPEG || st->codec.codec_id == CODEC_ID_MPEG4) {
         if (ap) {
             st->codec.frame_rate = ap->frame_rate;
         } else {
@@ -233,6 +240,17 @@ AVOutputFormat h263_oformat = {
     raw_write_trailer,
 };
 
+AVInputFormat m4v_iformat = {
+    "m4v",
+    "raw MPEG4 video format",
+    0,
+    mpegvideo_probe,
+    video_read_header,
+    raw_read_packet,
+    raw_read_close,
+    value: CODEC_ID_MPEG4,
+};
+
 AVOutputFormat m4v_oformat = {
     "m4v",
     "raw MPEG4 video format",
@@ -434,6 +452,7 @@ int raw_init(void)
 
     av_register_output_format(&h263_oformat);
     
+    av_register_input_format(&m4v_iformat);
     av_register_output_format(&m4v_oformat);
 
     av_register_input_format(&mpegvideo_iformat);
diff --git a/libavcodec/h263dec.c b/libavcodec/h263dec.c
index 0d83a5633f..4b30180db4 100644
--- a/libavcodec/h263dec.c
+++ b/libavcodec/h263dec.c
@@ -110,6 +110,23 @@ static int h263_decode_end(AVCodecContext *avctx)
     return 0;
 }
 
+/**
+ * retunrs the number of bytes consumed for building the current frame
+ */
+static int get_consumed_bytes(MpegEncContext *s, int buf_size){
+    int pos= (get_bits_count(&s->gb)+7)>>3;
+
+    if(s->divx_version>=500){
+        //we would have to scan through the whole buf to handle the weird reordering ...
+        return buf_size; 
+    }else{
+        if(pos==0) pos=1; //avoid infinite loops (i doubt thats needed but ...)
+        if(pos>buf_size) pos=buf_size; // oops ;)
+
+        return pos;
+    }
+}
+
 static int h263_decode_frame(AVCodecContext *avctx, 
                              void *data, int *data_size,
                              UINT8 *buf, int buf_size)
@@ -179,20 +196,20 @@ uint64_t time= rdtsc();
             return -1;
     }
 
-    if(ret==FRAME_SKIPED) return buf_size;
+    if(ret==FRAME_SKIPED) return get_consumed_bytes(s, buf_size);
     /* skip if the header was thrashed */
     if (ret < 0){
         fprintf(stderr, "header damaged\n");
         return -1;
     }
     /* skip b frames if we dont have reference frames */
-    if(s->num_available_buffers<2 && s->pict_type==B_TYPE) return buf_size;
+    if(s->num_available_buffers<2 && s->pict_type==B_TYPE) return get_consumed_bytes(s, buf_size);
     /* skip b frames if we are in a hurry */
-    if(s->hurry_up && s->pict_type==B_TYPE) return buf_size;
+    if(s->hurry_up && s->pict_type==B_TYPE) return get_consumed_bytes(s, buf_size);
     
     if(s->next_p_frame_damaged){
         if(s->pict_type==B_TYPE)
-            return buf_size;
+            return get_consumed_bytes(s, buf_size);
         else
             s->next_p_frame_damaged=0;
     }
@@ -354,14 +371,14 @@ uint64_t time= rdtsc();
         if(msmpeg4_decode_ext_header(s, buf_size) < 0) return -1;
     
     /* divx 5.01+ bistream reorder stuff */
-    if(s->codec_id==CODEC_ID_MPEG4 && s->bitstream_buffer_size==0){
+    if(s->codec_id==CODEC_ID_MPEG4 && s->bitstream_buffer_size==0 && s->divx_version>=500){
         int current_pos= get_bits_count(&s->gb)>>3;
 
         if(   buf_size - current_pos > 5 
            && buf_size - current_pos < BITSTREAM_BUFFER_SIZE){
             int i;
             int startcode_found=0;
-            for(i=current_pos; i<buf_size; i++){
+            for(i=current_pos; i<buf_size-3; i++){
                 if(buf[i]==0 && buf[i+1]==0 && buf[i+2]==1 && buf[i+3]==0xB6){
                     startcode_found=1;
                     break;
@@ -454,7 +471,7 @@ uint64_t time= rdtsc();
 #ifdef PRINT_FRAME_TIME
 printf("%Ld\n", rdtsc()-time);
 #endif
-    return buf_size;
+    return get_consumed_bytes(s, buf_size);
 }
 
 AVCodec mpeg4_decoder = {