[FFmpeg-trac] #3634(avformat:closed): asfenc: too many payloads in a packet

[FFmpeg]

#3634: asfenc: too many payloads in a packet
------------------------------------+------------------------------------
             Reporter:  atgraham    |                    Owner:
                 Type:  defect      |                   Status:  closed
             Priority:  normal      |                Component:  avformat
              Version:  git-master  |               Resolution:  fixed
             Keywords:  asf         |               Blocked By:
             Blocking:              |  Reproduced by developer:  1
Analyzed by developer:  0           |
------------------------------------+------------------------------------
Changes (by cehoyos):

 * keywords:   => asf
 * version:  unspecified => git-master


Old description:

> In the ASF specification:
> http://www.microsoft.com/en-us/download/details.aspx?id=14995
>
> the section on Multiple payloads (5.2.3.3) describes the bit fields used
> to specify payload length type and number of payloads. The number of
> payloads field is a 6-bit field, meaning a packet can hold a maximum of
> 63 payloads.
>
> asfenc.c was not honoring this, and if more than 63 payloads would fit in
> a packet, the "number of payloads" field would overflow into the "payload
> length type" field, causing parsing errors in ffplay.
>
> You can reproduce this with any AAC file that has several seconds of
> silence in the beginning (lots of very small AAC frames). Use this ffmpeg
> command:
>
> $ ffmpeg -i silence.m4a -acodec copy silence.asf
>
> Note that ffplay will get lots of errors.
>
> Anyway, here's a patch to fix the problem. I already submitted this to
> ffmpeg-devel.
>
> diff -ur ffmpeg-mine/libavformat/asfenc.c
> ffmpeg-2.2.2/libavformat/asfenc.c
> --- ffmpeg-mine/libavformat/asfenc.c    2014-05-12 15:23:12.093259469
> -0700
> +++ ffmpeg-2.2.2/libavformat/asfenc.c   2014-05-04 21:14:52.000000000
> -0700
> @@ -34,7 +34,6 @@
>
>  #define ASF_INDEXED_INTERVAL    10000000
>  #define ASF_INDEX_BLOCK         (1<<9)
> -#define ASF_PAYLOADS_PER_PACKET 63
>
>  #define ASF_PACKET_ERROR_CORRECTION_DATA_SIZE 0x2
>  #define ASF_PACKET_ERROR_CORRECTION_FLAGS          \
> @@ -819,8 +818,6 @@
>              flush_packet(s);
>          else if (asf->packet_size_left <=
> (PAYLOAD_HEADER_SIZE_MULTIPLE_PAYLOADS + PACKET_HEADER_MIN_SIZE + 1))
>              flush_packet(s);
> -        else if (asf->packet_nb_payloads == ASF_PAYLOADS_PER_PACKET)
> -            flush_packet(s);
>      }
>      stream->seq++;
>  }

New description:

 In the ASF specification:
 http://www.microsoft.com/en-us/download/details.aspx?id=14995

 the section on Multiple payloads (5.2.3.3) describes the bit fields used
 to specify payload length type and number of payloads. The number of
 payloads field is a 6-bit field, meaning a packet can hold a maximum of 63
 payloads.

 asfenc.c was not honoring this, and if more than 63 payloads would fit in
 a packet, the "number of payloads" field would overflow into the "payload
 length type" field, causing parsing errors in ffplay.

 You can reproduce this with any AAC file that has several seconds of
 silence in the beginning (lots of very small AAC frames). Use this ffmpeg
 command:

 $ ffmpeg -i silence.m4a -acodec copy silence.asf

 Note that ffplay will get lots of errors.

 Anyway, here's a patch to fix the problem. I already submitted this to
 ffmpeg-devel.
 {{{
 diff -ur ffmpeg-mine/libavformat/asfenc.c
 ffmpeg-2.2.2/libavformat/asfenc.c
 --- ffmpeg-mine/libavformat/asfenc.c    2014-05-12 15:23:12.093259469
 -0700
 +++ ffmpeg-2.2.2/libavformat/asfenc.c   2014-05-04 21:14:52.000000000
 -0700
 @@ -34,7 +34,6 @@

  #define ASF_INDEXED_INTERVAL    10000000
  #define ASF_INDEX_BLOCK         (1<<9)
 -#define ASF_PAYLOADS_PER_PACKET 63

  #define ASF_PACKET_ERROR_CORRECTION_DATA_SIZE 0x2
  #define ASF_PACKET_ERROR_CORRECTION_FLAGS          \
 @@ -819,8 +818,6 @@
              flush_packet(s);
          else if (asf->packet_size_left <=
 (PAYLOAD_HEADER_SIZE_MULTIPLE_PAYLOADS + PACKET_HEADER_MIN_SIZE + 1))
              flush_packet(s);
 -        else if (asf->packet_nb_payloads == ASF_PAYLOADS_PER_PACKET)
 -            flush_packet(s);
      }
      stream->seq++;
  }
 }}}

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Ticket URL: <https://trac.ffmpeg.org/ticket/3634#comment:2>
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