[FFmpeg-devel] [PATCH] missing last frame for h264 decoding + CODEC_FLAG_TRUNCATED

[Pascal Massimino]

  Michael,

On Sat, May 24, 2008 at 2:53 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> On Fri, May 23, 2008 at 01:36:13PM -0700, Pascal Massimino wrote:
>>   Hi everybody,
>>
>>   attached a patch for h264 decoding in CODEC_FLAG_TRUNCATED mode:
>>   even during the last call to decode_frame() with buf_size = 0, i'd say
>>   we need to flush the buffers in the ParseContext before calling it
>> quit for good.
>>
>>   Also: when flushing (for seek), we need to wipe the ParseContext too, to
>>   get rid of pending frame fragments.
>>
>>   I've uploaded a very small 'test_2frames.264' raw h264 file into incoming/
>>   on the ftp.
>>   Without this patch, repeated call to decode_frame() wouldn't decode the
>>   last frame.
>>
>> skal
>
>> --- h264.c.orig       2008-05-20 08:15:32.673356000 -0700
>> +++ h264.c    2008-05-23 13:26:22.272216000 -0700
>> @@ -3314,6 +3314,9 @@
>>          h->s.current_picture_ptr->reference= 0;
>>      h->s.first_field= 0;
>>      ff_mpeg_flush(avctx);
>> +    if (h->s.flags&CODEC_FLAG_TRUNCATED){
>> +        memset(&h->s.parse_context, 0, sizeof(h->s.parse_context));
>> +    }
>
> ff_mpeg_flush() should already clean parse_context, the memset might
> instead result in a memleak

 indeed. Removed.

>
>
>>  }
>>
>>  /**
>> @@ -7655,6 +7658,21 @@
>>      s->flags= avctx->flags;
>>      s->flags2= avctx->flags2;
>>
>> +    if(s->flags&CODEC_FLAG_TRUNCATED){
>> +        int next;
>> +        uint8_t tmp[FF_INPUT_BUFFER_PADDING_SIZE] = { 0 };
>
>> +        if (buf_size > 0) {
>> +            next= ff_h264_find_frame_end(h, buf, buf_size);
>> +        } else {
>> +            buf= tmp;
>> +            next= END_NOT_FOUND;
>> +        }
>
> ff_h264_find_frame_end(, , 0) should return END_NOT_FOUND
> and buf should not be used with buf_size=0 thus it shouldnt matter what its
> value is i think

 i'd say ff_combine_patch needs a small fix for that (attached: parser.patch).
 Updated the original patch (trunc.patch)

skal
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