[Libav-user] Create a muxer without enc_ctx = out_stream->codec

[Charles]

Many things for the input.

I removed the codepar stuff and the extra sets on the av_encode_codec_ctx
Also removed avcodec_parameters_to_context

Now I end up where I started, that the output ctx fails...
Stream #0:0: Unknown: none (h264_nvenc)
[mp4 @ 0x1277d60] Using AVStream.codec to pass codec parameters to muxers is deprecated, use AVStream.codecpar instead.
[mp4 @ 0x1277d60] dimensions not set

How do I get from avformat_new_stream to avformat_write_header?

avcodec_find_encoder
avformat_alloc_output_context2
   avformat_new_stream /// Tried at multiple locations
av_dict_set
avcodec_alloc_context3
    /// tried new stream here
set codec ctx
avcodec_open2
    /// tried new stream here
avio_open
avformat_write_header

It seems like my output context does not use the encoder ctx for information???

Thanks
cco


On 08/23/2016 09:47 AM, Nicolas George wrote:
> Le septidi 7 fructidor, an CCXXIV, Charles a écrit :
>> 4) parameters = video_st->codecpar;
>>    parameters->codec_tag = tag;
>>    parameters->format    = AV_PIX_FMT_YUV420P;
>>    parameters->bit_rate  = 5e6;
>>    parameters->width     = 1024;
>>    parameters->height    = 768;
>>    parameters->bit_rate  = 5e6;
>
> You are not supposed to fill the stream's parameters with random values, you
> are supposed to fill them with the values used by the encoder. These values
> will be very similar to the settings you chose for the encoder, but the
> encoder is allowed to tweak them.
>
>> 5) av_encode_codec_ctx = avcodec_alloc_context3( av_encode_codec )
>>    av_encode_codec_ctx->bit_rate    = 5e6;
>>    av_encode_codec_ctx->width       = 1024;   /// \note multiple of 2
>>    av_encode_codec_ctx->height      = 768;   /// \note multiple of 2
>>    av_encode_codec_ctx->time_base   = (AVRational) { 1, 60 }; //* 2;
>>    av_encode_codec_ctx->gop_size    = 15;      // Intra frames per x P frames
>>    av_encode_codec_ctx->pix_fmt     = AV_PIX_FMT_YUV420P; // MUST DO NOT CHANGE nvenc required
>>    // This appears to make h264_nvenc happy
>> 6) avcodec_parameters_to_context( av_encode_codec_ctx, parameters )
>
> You are still overwriting the parameters of the encoder. It can not work.
> The parameters are used for communication from demuxers to decoders and from
> encoders to muxers. They are output from the decoders and you are using them
> as input.
>
> Regards,
>