[Libav-user] Decoding single NALUs from x264 programmatically (no luck even with parser), works fine with concatenated NALUs

[Faraz Khan]

Sergey,
I did not - is that supposed to do the trick? Would we need a parser in
that scenario?



On Sun, Jul 7, 2013 at 12:13 AM, Sergey Fedorov <
night.rain.whisper at gmail.com> wrote:

> Did you try using CODEC_FLAG2_CHUNKS?
>
>
> 2013/7/6 Attila Sukosd <attila.sukosd at gmail.com>
>
>> Hi guys,
>>
>> There was this thread about decoding NALUs one-by-one with
>> parser2/decode2 and I'm having exactly the same issue.
>>
>> I have x264 creating a bunch of NALUs, in annex_b and repeate_headers,
>> and trying to decode them one by one on the client side. When I concatenate
>> all the NALUs per frame into one large packet, and feed that directly into
>> avcodec_decode_video2, everything is fine, the decode is successful.
>> However, when I try to feed single NALs directly to
>> avcodec_decode_video2, it spits out a bunch of errors. After searching for
>> a while on the net, I read some place that certain types of NALs affect the
>> rest of the data stream, and they need to be group together.
>> I've tried to run the NALs through av_parser_parse2 and tried to decode
>> the output buffer when the output size was larger than zero, however, after
>> looking at the output buffer contents, it seems like while the output size
>> seems reasonable (around the size of the NALs or a combination of a number
>> of previous NALs), the output buffer content contains 3-4 bytes, and the
>> rest is zero.
>>
>> The decoding looks like this:
>>
>>  ret = av_parser_parse2(decoder->pParserCtx, decoder->pCodecCtx,
>> decoder->tmp_data, &outsize, buff, size, 0, 0, AV_NOPTS_VALUE);
>>  printf("%p buff, %p outdata, consumed %d, %d bufsize, %d outsize\n",
>> buff, decoder->tmp_data,ret, size, outsize);
>>  disp_buff(decoder->tmp_data, 50);
>>
>>  if (outsize <= 0) return 0;
>>
>>  decoder->avpkt.flags = AV_PKT_FLAG_KEY;
>>  decoder->avpkt.data = decoder->tmp_data;
>>  decoder->avpkt.size = outsize;
>>
>>   got_picture = 0;
>>   if ((ret = avcodec_decode_video2(decoder->pCodecCtx, decoder->pFrame,
>> &got_picture, &decoder->avpkt)) < 0) {
>>                 LOGE(__FUNCTION__, "H264 decoding failed!\n");
>>                 return -1;
>>   }
>>
>>
>> Could someone shed some light on if I'm really off the right track? or am
>> I just missing something very trivial?
>>
>>
>> Best Regards,
>>
>> Attila
>>
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>>
>
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Faraz Khan
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