[FFmpeg-devel] [PATCH] asf muxer: gracefully handle negative timestamps

[Vladimir Pantelic]

Michael Niedermayer wrote:
> On Thu, Mar 11, 2010 at 12:15:16PM +0100, Vladimir Pantelic wrote:
>>  I have one asf file that when remuxed to asf with vcodec/acodec copy for
>>  some reason has negative dts.
>>
>>  These negative dts end up in "sendtime" as a large integer, putting the
>>  send
>>  time in future of the payload presentation time. This is due to the fact
>>  that (int)asf->packet_timestamp_start is converted to (unsigned
>>  int)sendtime
>>
>>  Attached patch make sure that we write a sendtime of 0 in this case.
>>
>>  This fixes some complaints that M$ "Windows Media ASF View 9 Series" has
>>  with the generated file.
>
>>   asfenc.c |    4 ++--
>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>  5a18e0df6769452b2874689888dfdd832cca85dc  asf_fix_send_time.patch
>>  Index: libavformat/asfenc.c
>>  ===================================================================
>>  --- libavformat/asfenc.c	(revision 22465)
>>  +++ libavformat/asfenc.c	(working copy)
>>  @@ -585,7 +624,7 @@
>>
>>   static int put_payload_parsing_info(
>>                                   AVFormatContext *s,
>>  -                                unsigned int    sendtime,
>>  +                                int             sendtime,
>>                                   unsigned int    duration,
>>                                   int             nb_payloads,
>>                                   int             padsize
>>  @@ -626,7 +665,7 @@
>>       if (iLengthTypeFlags&  ASF_PPI_FLAG_PADDING_LENGTH_FIELD_IS_BYTE)
>>           put_byte(pb, padsize - 1);
>>
>>  -    put_le32(pb, sendtime);
>>  +    put_le32(pb, FFMAX(0, sendtime));
>
> muxers are not supposed to store random values
>
> id suggest
> 1. add a flag to muxers specifying the capability of negative dts support

add AVFMT_POSITIVE_TIMESTAMPS to asfenc, or AVFMT_NEGATIVE_TIMESTAMPS
to all others?

> 2. check for that flag in common code (utils.c) and offset all timestamps
>     so as to avoid neagative dts if not set
>
> [...]
>
>
>
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at mplayerhq.hu
> https://lists.mplayerhq.hu/mailman/listinfo/ffmpeg-devel