[FFmpeg-devel] [PATCH 3/4] fftools/ffmpeg: support variable dimension encode

[James Almer]

On 7/29/2019 11:44 AM, Linjie Fu wrote:
> Flush encoders when dimension change happens, reset draining to resume
> encode.
> 
> If encoder doesn't support variable dimension, stop encoding and
> report errors.
> 
> Signed-off-by: Linjie Fu <linjie.fu at intel.com>
> ---
>  fftools/ffmpeg.c    | 13 +++++++++++++
>  libavcodec/encode.c |  4 ++++
>  2 files changed, 17 insertions(+)
> 
> diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
> index 5d52430..8ceeaaa 100644
> --- a/fftools/ffmpeg.c
> +++ b/fftools/ffmpeg.c
> @@ -130,6 +130,7 @@ static void do_video_stats(OutputStream *ost, int frame_size);
>  static BenchmarkTimeStamps get_benchmark_time_stamps(void);
>  static int64_t getmaxrss(void);
>  static int ifilter_has_all_input_formats(FilterGraph *fg);
> +static void flush_encoders(void);
>  
>  static int run_as_daemon  = 0;
>  static int nb_frames_dup = 0;
> @@ -1067,6 +1068,18 @@ static void do_video_out(OutputFile *of,
>      InputStream *ist = NULL;
>      AVFilterContext *filter = ost->filter->filter;
>  
> +    /* flush encoders in dynamic resolution encode */
> +    if (next_picture && (enc->width != next_picture->width ||
> +                         enc->height != next_picture->height)) {
> +        flush_encoders();
> +
> +        if (!(enc->codec->capabilities & AV_CODEC_CAP_VARIABLE_DIMENSIONS)) {
> +            av_log(NULL, AV_LOG_ERROR, "Dynamic resolution encode "
> +                            "is not supported by %s.\n", enc->codec->name);
> +            goto error;
> +        }
> +    }
> +
>      if (ost->source_index >= 0)
>          ist = input_streams[ost->source_index];
>  
> diff --git a/libavcodec/encode.c b/libavcodec/encode.c
> index d12c425..9303bc9 100644
> --- a/libavcodec/encode.c
> +++ b/libavcodec/encode.c
> @@ -389,6 +389,10 @@ int attribute_align_arg avcodec_send_frame(AVCodecContext *avctx, const AVFrame
>      if (!avcodec_is_open(avctx) || !av_codec_is_encoder(avctx->codec))
>          return AVERROR(EINVAL);
>  
> +    /* reset draining when encoder is flushed in variable dimensions encoding */
> +    if (frame)
> +        avctx->internal->draining = 0;

This is an API change that can break some workflows.

avcodec_flush_buffers() is the public function meant to flush an
AVCodecContext.

> +
>      if (avctx->internal->draining)
>          return AVERROR_EOF;
>  
>