[FFmpeg-devel] [PATCH] avformat/matroska: Parse generic encryption info from packets.

[James Almer]

On 8/14/2018 12:50 AM, James Almer wrote:
> On 7/12/2018 8:45 PM, Jacob Trimble wrote:
>> I am currently seeing a problem with this when using Opus audio.  In
>> read_frame_internal, it will try to parse the resulting packet.  For
>> video, which uses subsample encryption, it is able to parse the
>> headers; but for Opus, which uses full-sample encryption, it fails to
>> parse the headers.  This causes the read_frame_internal to drop the
>> packet.
>>
>> I have traced a workaround to opus_parse in opus_parser.c: instead of
>> setting poutbuf to NULL, set it to the buffer and just pass the packet
>> to the app to handle it.  The frame will be decrypted before passing
>> to the decoder.  I can't just disable parsing in the demuxer because I
>> want to parse the packets for clear content and when using subsample
>> encryption.
>>
>> Does anyone have any other ideas to work around this?  Is there a way
>> to allow parsing but ignore errors?
> Try the attached diff to see if it fixes the issue (It makes the parser
> not bother trying to assemble packets from what could be incomplete data
> if the source is a demuxer that guarantees the propagation of complete
> packets).
> 
> 
> opus.diff
> 
> 
> diff --git a/libavcodec/opus_parser.c b/libavcodec/opus_parser.c
> index 28b0933900..e8d157356c 100644
> --- a/libavcodec/opus_parser.c
> +++ b/libavcodec/opus_parser.c
> @@ -170,6 +170,9 @@ static int opus_parse(AVCodecParserContext *ctx, AVCodecContext *avctx,
>      ParseContext *pc    = &s->pc;
>      int next, header_len;

Err, with the change below this should be initialized to 0 now. Sorry.

>  
> +    if (s->flags & PARSER_FLAG_COMPLETE_FRAMES) {
> +        next = buf_size;
> +    } else {
>      next = opus_find_frame_end(ctx, avctx, buf, buf_size, &header_len);
>  
>      if (s->ts_framing && next != AVERROR_INVALIDDATA &&
> @@ -184,6 +187,7 @@ static int opus_parse(AVCodecParserContext *ctx, AVCodecContext *avctx,
>          *poutbuf_size = 0;
>          return buf_size;
>      }
> +    }
>  
>      *poutbuf      = buf + header_len;
>      *poutbuf_size = buf_size - header_len;
>