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

[Faraz Khan]

Also - av_parser_parse2 doesnt seem to like out of order NAL packets - is
this also a known issue?



On Mon, Jun 10, 2013 at 3:43 PM, Faraz Khan <faraz at screenhero.com> wrote:

> So I got the decoder to work with the parser! It was a bug on my end -
> However it still seems that the parser waits for the entire frame to
> complete and then sets an outsize? Is this intentional? Is it possible to
> decode a single NALU?
>
>
>
> On Mon, Jun 10, 2013 at 2:57 PM, Faraz Khan <faraz at screenhero.com> wrote:
>
>> So the keyframe cannot be fed to the decoder one nal at a time? Is that
>> what you are suggesting?
>>
>>
>>
>>
>> On Mon, Jun 10, 2013 at 2:40 PM, Andy Shaules <bowljoman at gmail.com>wrote:
>>
>>>  I always had to decode from the latest key frame up to the desired
>>> stream time nal,
>>>
>>>
>>> On 6/10/2013 2:36 PM, Faraz Khan wrote:
>>>
>>> Hi all,
>>> I'm trying to use ffmpeg as a decoder for a real-time x264 stream that
>>> I'm generating. It works fine if I try to decode entire frames, but if I
>>> try to decode a single NALU the decoder errors out saying 'no frame'. I've
>>> tried using the parser (av_parser_parse2) but the h264 decoder doesnt seem
>>> to like that output either. I'm using x264 with annex-b and repeat-headers
>>> on.
>>>
>>>  The encoder config is as follows:
>>>
>>> x264params.b_sliced_threads = 1;
>>> x264params.i_slice_max_size = 1350;
>>> x264params.i_width = yuvSize.width;
>>> x264params.i_height = yuvSize.height;
>>> x264params.i_fps_num = 10;
>>> x264params.i_fps_den = 1;
>>> x264params.b_vfr_input = 0;
>>> x264params.rc.i_bitrate = 1500;
>>>
>>>   // Intra refres:
>>> x264params.i_keyint_max = 50000000;
>>> x264params.b_intra_refresh = 1;
>>>
>>>  //Rate control:
>>>
>>> x264params.rc.i_rc_method = X264_RC_ABR;
>>> x264params.rc.i_vbv_buffer_size = 300;
>>> x264params.rc.i_vbv_max_bitrate = 1500;
>>>
>>>  //For streaming:
>>> x264params.b_repeat_headers = 1;
>>> x264params.b_annexb = 1;
>>>
>>>  x264_param_apply_profile(&x264params, "baseline");
>>>
>>>
>>>
>>>  I do the encode with:
>>>
>>>     int frame_size = x264_encoder_encode(x264Encoder, &nals, &i_nals, &
>>> pic_in, &pic_out);
>>>
>>>
>>>  Now, since the max slice size is 1350, each packet output is a udp
>>> packet of size < MTU (this is true) and sent across the network.
>>>
>>> I iterate over the nals[i].p_payload and send them over to the ffmpeg
>>> side for decoding. I receive the correct packet on the remote side.
>>>
>>> If I assemble ALL the NALUs that were output in this frame and feed it
>>> directly to the decoder (even without the parser), it works fine! If I feed
>>> one NALU at a time, it fails (event with the parse). I'm sending it to the
>>> parser like:
>>>
>>>
>>>  int plen = av_parser_parse2(codecParser, decoderContext, &outbuf,
>>> &outside, indata,inlength,0,0,0);
>>>
>>>
>>>  plen always reports that it consumed the entire NALU that I gave it -
>>> after consuming a few NALUs, the outsize and outbuf are set to some value.
>>> Feeding it into the decoder using:
>>>
>>>
>>>   int len = avcodec_decode_video2(decoderContext,decoderOutframe,
>>> &gotpic,&avpkt);
>>>
>>>
>>>  Results in it saying 'No frame'. Again, if avpkt.data contains the
>>> entire frame (all NALUs concatenated) it will work!
>>>
>>>
>>>  I'm obviously doing some obviously wrong - but I really cant figure
>>> out why it wont decode a single NALU. Or is this a limitation in ffmpeg?
>>>
>>>
>>>  Thanks Guys!
>>>
>>>
>>>
>>>
>>> --
>>> Faraz Khan
>>> Simple Collaboration Screensharing
>>> www.screenhero.com
>>>
>>>
>>> _______________________________________________
>>> Libav-user mailing listLibav-user at ffmpeg.orghttp://ffmpeg.org/mailman/listinfo/libav-user
>>>
>>>
>>>
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>>>
>>>
>>
>>
>> --
>>
>> --
>> Faraz Khan
>> Simple Collaboration Screensharing
>> www.screenhero.com
>>
>
>
>
> --
>
> --
> Faraz Khan
> Simple Collaboration Screensharing
> www.screenhero.com
>



-- 

--
Faraz Khan
Simple Collaboration Screensharing
www.screenhero.com
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