[Ffmpeg-devel] [PATCH] ffmpeg.c: raw subtitles stream support; vhook crashed if -vcodec copy

Alexey Sidelnikov avs99
Wed Oct 25 11:04:12 CEST 2006

sorry for raising the same issue again, but last time i failed to attach 
a patch file: http://article.gmane.org/gmane.comp.video.ffmpeg.devel/38695

I will duplicate my old message here if you don't mind.

I'm sorry, there are two non-related patches in one diff, but both are 
very simple, and both are for ffmpeg.c, so I hope that is okay.

1. First patch is to allow raw subtitle stream copying. It was proposed
originally here:


but the author missed that if there is no subtitles at all in the input
file, then ffmpeg will crash. So I just added one more check to 
av_encode() function.

2. Following this topic:


if pre_process_video_frame() is called when video stream is copied, then
AVPicture is not valid in it, and ffmpeg will crash. I added 2 checks - 
one in av_encode() during streams sanity check - that will notify a user 
right now, and the other one just before pre_process_video_frame() call 
- to make sure ffmpeg won't crash somewhere in the future, when a new 
pre_process command will be added.


Index: ffmpeg.c
--- ffmpeg.c	(revision 6731)
+++ ffmpeg.c	(working copy)
@@ -1150,8 +1150,12 @@

              buffer_to_free = NULL;
              if (ist->st->codec->codec_type == CODEC_TYPE_VIDEO) {
-                pre_process_video_frame(ist, (AVPicture *)&picture,
-                                        &buffer_to_free);
+                if (ist->decoding_needed) {
+                    pre_process_video_frame(ist, (AVPicture *)&picture, 
+                }
+                else {
+                    fprintf(stderr, "video frame can not be 
preprocessed if video stream is copied\n");
+                }

              // preprocess audio (volume)
@@ -1427,6 +1431,12 @@
          os = output_files[i];
          nb_ostreams += os->nb_streams;
+    if (nb_ostreams == 0) {
+        fprintf(stderr, "No audio, video or subtitles streams 
+        exit(1);
+    }
      if (nb_stream_maps > 0 && nb_stream_maps != nb_ostreams) {
          fprintf(stderr, "Number of stream maps must match number of 
output streams\n");
@@ -1544,6 +1554,11 @@
                  codec->block_align= icodec->block_align;
              case CODEC_TYPE_VIDEO:
+                if (do_deinterlace || using_vhook) {
+                    fprintf(stderr, "Neither deinterlace, nor vhook are 
allowed during video stream copying!\nDecoding/encoding is required.\n");
+                    exit(1);
+                }
                  codec->pix_fmt = icodec->pix_fmt;
                  codec->width = icodec->width;
                  codec->height = icodec->height;

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