[FFmpeg-devel] [PATCH 1/4] ffmpeg: re-copy codec contexts after encoding

[James Almer]

On 9/26/2016 2:13 PM, Jon Toohill wrote:
> This preserves changes to fields of AVCodecContext that get
> updated during encoding, such as trailing_padding (which
> may not be known until encoding is complete).
> ---
>  ffmpeg.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/ffmpeg.c b/ffmpeg.c
> index df55a49..1e973f5 100644
> --- a/ffmpeg.c
> +++ b/ffmpeg.c
> @@ -4243,6 +4243,21 @@ static int transcode(void)
>  
>      term_exit();
>  
> +    /* update output codec contexts after encoding */
> +    for (i = 0; i < nb_output_streams; i++) {
> +        ost = output_streams[i];
> +        if (ost->encoding_needed) {
> +            ret = avcodec_copy_context(
> +                output_files[ost->file_index]->ctx->streams[ost->index]->codec,
> +                ost->enc_ctx);

We ported ffmpeg to codecpar, so AVStream.codec shouldn't be used anymore.

While i can't say if adding this chunk here is a good idea or even correct
to begin with, you should in any case use avcodec_parameters_from_context()
to copy parameters to the output stream's codecpar context.

> +            if (ret < 0) {
> +                av_log(ost, AV_LOG_ERROR, "Error copying final codec context: %s\n", av_err2str(ret));
> +                if (exit_on_error)
> +                    exit_program(1);
> +            }
> +        }
> +    }
> +
>      /* write the trailer if needed and close file */
>      for (i = 0; i < nb_output_files; i++) {
>          os = output_files[i]->ctx;
>