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Tue Jan 23 19:03:48 CET 2007 · https://ffmpeg.org/pipermail/ffmpeg-devel/2007-January/027830.html

Wolfram Gloger wrote:
> Hi,
>
>   
>> I first got the most recent svn to my home directory.  Then, I copied 
>> the patch file to my home directory. I used the command "patch -p0 < 
>> patch.diff" to apply the patch, then ran configure --enable-mp3lame and 
>> then make.
>>     
>
> That is correct if you intend to change sources in the 'trunk'
> directory, and configure and compile within the 'trunk' directory.
>
> Actually I missed adding a prototype for av_get_cur_dts as an exercise
> for the reader :-/.  Sorry.  Perhaps that is the reason for your
> continued problem?
>
> Augmented patch attached.
>
> Regards,
> Wolfram.
>
> diff -ur trunk/libavformat/avformat.h ffmpeg-wg/libavformat/avformat.h
> --- trunk/libavformat/avformat.h	Sun Dec 24 11:06:34 2006
> +++ ffmpeg/libavformat/avformat.h	Tue Jan 16 10:14:05 2007
> @@ -437,6 +437,8 @@
>                         int64_t pos, int64_t timestamp, int size, int distance, int flags);
>  int av_seek_frame_binary(AVFormatContext *s, int stream_index, int64_t target_ts, int flags);
>  void av_update_cur_dts(AVFormatContext *s, AVStream *ref_st, int64_t timestamp);
> +/* current dts in AV_TIME_BASE units */
> +int64_t av_get_cur_dts(AVFormatContext *s, int stream_index);
>  int64_t av_gen_search(AVFormatContext *s, int stream_index, int64_t target_ts, int64_t pos_min, int64_t pos_max, int64_t pos_limit, int64_t ts_min, int64_t ts_max, int flags, int64_t *ts_ret, int64_t (*read_timestamp)(struct AVFormatContext *, int , int64_t *, int64_t ));
>  
>  /* media file output */
> diff -ur trunk/ffmpeg.c ffmpeg/ffmpeg.c
> --- trunk/ffmpeg.c	Sat Jan 13 20:47:31 2007
> +++ ffmpeg/ffmpeg.c	Tue Jan 16 10:46:51 2007
> @@ -2613,6 +2613,16 @@
>          }
>          /* reset seek info */
>          start_time = 0;
> +        if (av_get_cur_dts(ic, -1) != AV_NOPTS_VALUE) {
> +            timestamp = av_get_cur_dts(ic, -1);
> +            fprintf(stderr, "*** after seek timestamp= %lld\n", timestamp);
> +        }
> +        /* reload stream parameters */
> +        ret = av_find_stream_info(ic);
> +        if (ret < 0 && verbose >= 0) {
> +            fprintf(stderr, "%s: could not find codec parameters\n", filename);
> +            exit(1);
> +        }
>      }
>  
>      /* update the current parameters so that they match the one of the input stream */
> diff -ur trunk/libavformat/avidec.c ffmpeg/libavformat/avidec.c
> --- trunk/libavformat/avidec.c	Tue Jan 16 09:34:41 2007
> +++ ffmpeg/libavformat/avidec.c	Tue Jan 16 10:34:16 2007
> @@ -26,8 +26,8 @@
>  #undef NDEBUG
>  #include <assert.h>
>  
> -//#define DEBUG
> -//#define DEBUG_SEEK
> +#define DEBUG
> +#define DEBUG_SEEK
>  
>  typedef struct AVIStream {
>      int64_t frame_offset; /* current frame (video) or byte (audio) counter
> @@ -961,7 +961,7 @@
>  
>  //        av_log(NULL, AV_LOG_DEBUG, "%"PRId64" %d %"PRId64"\n", timestamp, index, st2->index_entries[index].timestamp);
>          /* extract the current frame number */
> -        ast2->frame_offset = st2->index_entries[index].timestamp;
> +        st2->cur_dts = ast2->frame_offset = st2->index_entries[index].timestamp;
>          if(ast2->sample_size)
>              ast2->frame_offset *=ast2->sample_size;
>      }
> diff -ur trunk/libavformat/utils.c ffmpeg/libavformat/utils.c
> --- trunk/libavformat/utils.c	Mon Jan  8 16:01:14 2007
> +++ ffmpeg/libavformat/utils.c	Tue Jan 16 10:46:51 2007
> @@ -1437,6 +1437,27 @@
>          return av_seek_frame_generic(s, stream_index, timestamp, flags);
>  }
>  
> +/**
> + * Obtain the current dts in AV_TIME_BASE units.
> + * @param stream_index If stream_index is (-1), a default
> + * stream is selected.
> + */
> +int64_t av_get_cur_dts(AVFormatContext *s, int stream_index)
> +{
> +    AVStream *st;
> +
> +    if (stream_index < 0){
> +        stream_index= av_find_default_stream_index(s);
> +        if(stream_index < 0)
> +            return AV_NOPTS_VALUE;
> +    }
> +    st= s->streams[stream_index];
> +    if (st->cur_dts == AV_NOPTS_VALUE)
> +        return AV_NOPTS_VALUE;
> +    return av_rescale(st->cur_dts, AV_TIME_BASE * (int64_t)st->time_base.num,
> +                      st->time_base.den);
> +}
> +
>  /*******************************************************/
>  
>  /**
> @@ -1561,6 +1582,7 @@
>      int read_size, i, ret;
>      int64_t end_time;
>      int64_t filesize, offset, duration;
> +    offset_t old_offset;
>  
>      /* free previous packet */
>      if (ic->cur_st && ic->cur_st->parser)
> @@ -1580,7 +1602,8 @@
>  
>      /* we read the first packets to get the first PTS (not fully
>         accurate, but it is enough now) */
> -    url_fseek(&ic->pb, 0, SEEK_SET);
> +    old_offset = url_ftell(&ic->pb);
> +    url_fseek(&ic->pb, 0, SEEK_CUR);
>      read_size = 0;
>      for(;;) {
>          if (read_size >= DURATION_MAX_READ_SIZE)
> @@ -1646,7 +1669,7 @@
>  
>      fill_all_stream_timings(ic);
>  
> -    url_fseek(&ic->pb, 0, SEEK_SET);
> +    url_fseek(&ic->pb, old_offset, SEEK_SET);
>  }
>  
>  static void av_estimate_timings(AVFormatContext *ic)
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at mplayerhq.hu
> http://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel
>   
This patch worked for me, although there was some extra output during 
the cutting process that didn't look normal:

 /home/cyrus/ffmpeg/ffmpeg -ss 48.0 -t 25.8 -y -vcodec copy -acodec copy 
-i test.avi cutfile.avi
FFmpeg version SVN-r7669, Copyright (c) 2000-2006 Fabrice Bellard, et al.
  configuration:  --enable-mp3lame
  libavutil version: 49.2.0
  libavcodec version: 51.29.0
  libavformat version: 51.8.0
  built on Jan 23 2007 12:43:45, gcc: 4.1.1 20060525 (Red Hat 4.1.1-1)
tag: tag=LIST size=0x2276
list: tag=hdrl size=0x0
tag: tag=avih size=0x38
tag: tag=LIST size=0x1090
list: tag=strl size=0x0
tag: tag=strh size=0x38
strh: tag=vids size=0xffffffff
tag: tag=strf size=0x28
video: tag=DX50 size=0x0
tag: tag=JUNK size=0x1014
tag: tag=LIST size=0x1086
list: tag=strl size=0x0
tag: tag=strh size=0x38
strh: tag=auds size=0xffffffff
tag: tag=strf size=0x1e
tag: tag=JUNK size=0x1014
tag: tag=JUNK size=0x104
tag: tag=LIST size=0x18
list: tag=INFO size=0x0
tag: tag=ISFT size=0xb
tag: tag=JUNK size=0x3f8
tag: tag=LIST size=0x51b94c
list: tag=movi size=0x0
movi end=51dffe
movi_end=0x51dffe
tag=idx1 size=0x16ad0
*** after seek timestamp= 47781067

Seems stream 0 codec frame rate differs from container frame rate: 
30000.00 (30000/1) -> 29.97 (30000/1001)
Input #0, avi, from 'test.avi':
  Duration: 00:01:25.0, start: 0.000000, bitrate: 513 kb/s
  Stream #0.0: Video: mpeg4, yuv420p, 480x384, 29.97 fps(r)
  Stream #0.1: Audio: mp3, 44100 Hz, stereo, 192 kb/s
Output #0, avi, to 'cutfile.avi':
  Stream #0.0: Video: mpeg4, yuv420p, 480x384, q=2-31, 29.97 fps(c)
  Stream #0.1: Audio: mp3, 44100 Hz, stereo, 192 kb/s
Stream mapping:
  Stream #0.0 -> #0.0
  Stream #0.1 -> #0.1
Press [q] to stop encoding
frame=  774 q=0.0 Lsize=    1445kB time=25.8 bitrate= 458.8kbits/s   
video:789kB audio:604kB global headers:0kB muxing overhead 3.754022%

Aside from that debugging output, it worked fine. Can we add this patch 
to the main development branch so that future versions have the fix?

Cyrus

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[Ffmpeg-devel] corrupt audio when cut [SOLVED]