[vlc-devel] [PATCH] avcodec: added skip-frames option for encoder

Steve Lhomme robux4 at ycbcr.xyz
Thu Jul 26 08:58:04 CEST 2018


On 24/07/2018 21:59, PaweĊ‚ Wegner wrote:
> Encoder will encode only one frame per timestamp. Since timestamps may be
> inaccurate, skipping frames may render encoder's output nondeterministic.
> Added an option which instructs to encode all frames which come out of avcodec.

Is this related to the output of the avcodec decoder ? Because that's 
how I understand the commit log and doc of the option. But the option is 
on the encoder, which may receive frames from other decoders.

> ---
>   modules/codec/avcodec/avcodec.c |  3 +++
>   modules/codec/avcodec/avcodec.h |  6 ++++++
>   modules/codec/avcodec/encoder.c | 32 ++++++++++++++++++--------------
>   3 files changed, 27 insertions(+), 14 deletions(-)
>
> diff --git a/modules/codec/avcodec/avcodec.c b/modules/codec/avcodec/avcodec.c
> index 0e08c11fc6..d5df52871a 100644
> --- a/modules/codec/avcodec/avcodec.c
> +++ b/modules/codec/avcodec/avcodec.c
> @@ -235,6 +235,9 @@ vlc_module_begin ()
>                   ENC_PROFILE_TEXT, ENC_PROFILE_LONGTEXT, true )
>   
>       add_string( ENC_CFG_PREFIX "options", NULL, AV_OPTIONS_TEXT, AV_OPTIONS_LONGTEXT, true )
> +
> +    add_bool( ENC_CFG_PREFIX "skip-frames", true,
> +              ENC_SKIP_FRAMES_TEXT, ENC_SKIP_FRAMES_LONGTEXT, true )
>   #endif /* ENABLE_SOUT */
>   
>   #ifdef MERGE_FFMPEG
> diff --git a/modules/codec/avcodec/avcodec.h b/modules/codec/avcodec/avcodec.h
> index 52e522dc32..2900b86b3a 100644
> --- a/modules/codec/avcodec/avcodec.h
> +++ b/modules/codec/avcodec/avcodec.h
> @@ -233,6 +233,12 @@ int ffmpeg_OpenCodec( decoder_t *p_dec, AVCodecContext *, const AVCodec * );
>      "main, low, ssr (not supported),ltp, hev1, hev2 (default: low). " \
>      "hev1 and hev2 are currently supported only with libfdk-aac enabled libavcodec" )
>   
> +#define ENC_SKIP_FRAMES_TEXT N_( "Skip frames" )
> +#define ENC_SKIP_FRAMES_LONGTEXT N_( "Encoder will encode only one frame \
> +    per timestamp. Since timestamps may be inaccurate, skipping frames may \
> +    render encoder's output nondeterministic. Disable in order to encode all frames \
> +    which come out of avcodec." )
> +
>   #ifndef AV_VERSION_INT
>   #   define AV_VERSION_INT(a, b, c) ((a)<<16 | (b)<<8 | (c))
>   #endif
> diff --git a/modules/codec/avcodec/encoder.c b/modules/codec/avcodec/encoder.c
> index a00439e939..7c1082c099 100644
> --- a/modules/codec/avcodec/encoder.c
> +++ b/modules/codec/avcodec/encoder.c
> @@ -144,6 +144,7 @@ typedef struct
>       int        i_quality; /* for VBR */
>       float      f_lumi_masking, f_dark_masking, f_p_masking, f_border_masking;
>       int        i_aac_profile; /* AAC profile to use.*/
> +    bool       b_skip_frames;
>   
>       AVFrame    *frame;
>   } encoder_sys_t;
> @@ -193,7 +194,7 @@ static const char *const ppsz_enc_options[] = {
>       "interlace", "interlace-me", "i-quant-factor", "noise-reduction", "mpeg4-matrix",
>       "trellis", "qscale", "strict", "lumi-masking", "dark-masking",
>       "p-masking", "border-masking",
> -    "aac-profile", "options",
> +    "aac-profile", "options", "skip-frames",
>       NULL
>   };
>   
> @@ -419,6 +420,7 @@ int InitVideoEnc( vlc_object_t *p_this )
>       p_sys->f_rc_buffer_aggressivity = var_GetFloat( p_enc, ENC_CFG_PREFIX "rc-buffer-aggressivity" );
>       p_sys->f_i_quant_factor = var_GetFloat( p_enc, ENC_CFG_PREFIX "i-quant-factor" );
>       p_sys->b_mpeg4_matrix = var_GetBool( p_enc, ENC_CFG_PREFIX "mpeg4-matrix" );
> +    p_sys->b_skip_frames = var_GetBool( p_enc,  ENC_CFG_PREFIX "skip-frames" );
>   
>       f_val = var_GetFloat( p_enc, ENC_CFG_PREFIX "qscale" );
>   
> @@ -1213,21 +1215,23 @@ static block_t *EncodeVideo( encoder_t *p_enc, picture_t *p_pict )
>   
>           if ( ( frame->pts != AV_NOPTS_VALUE ) && ( frame->pts != VLC_TICK_INVALID ) )
>           {
> -            if ( p_sys->i_last_pts == frame->pts )
> +            if ( p_sys->b_skip_frames )
>               {
> -                msg_Warn( p_enc, "almost fed libavcodec with two frames with "
> -                          "the same PTS (%"PRId64 ")", frame->pts );
> -                return NULL;
> -            }
> -            else if ( p_sys->i_last_pts > frame->pts )
> -            {
> -                msg_Warn( p_enc, "almost fed libavcodec with a frame in the "
> -                         "past (current: %"PRId64 ", last: %"PRId64")",
> -                         frame->pts, p_sys->i_last_pts );
> -                return NULL;
> +                if ( p_sys->i_last_pts == frame->pts )
> +                {
> +                    msg_Warn( p_enc, "almost fed libavcodec with two frames with "
> +                            "the same PTS (%"PRId64 ")", frame->pts );
> +                    return NULL;
> +                }
> +                else if ( p_sys->i_last_pts > frame->pts )
> +                {
> +                    msg_Warn( p_enc, "almost fed libavcodec with a frame in the "
> +                            "past (current: %"PRId64 ", last: %"PRId64")",
> +                            frame->pts, p_sys->i_last_pts );
> +                    return NULL;
> +                }
>               }
> -            else
> -                p_sys->i_last_pts = frame->pts;
> +            p_sys->i_last_pts = frame->pts;
>           }
>   
>           frame->quality = p_sys->i_quality;
> -- 
> 2.17.1
>
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