[FFmpeg-devel] [PATCH] avcodec/libsvtav1: Add support for multipass encoding

[Lynne]

Sep 27, 2022, 23:06 by gustav.grusell at gmail.com:

> Implements support for 2-pass CRF and 3-pass VBR by implementing
> reading and writing of stats file, and passing the pass number on
> to the encoder. For 3-pass VBR, the first pass should be run with
> '-pass 1', the second with '-pass 3' and the third with '-pass 2'.
>
> Signed-off-by: Gustav Grusell <gustav.grusell at gmail.com>
> ---
>  libavcodec/libsvtav1.c | 82 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 82 insertions(+)
>
> diff --git a/libavcodec/libsvtav1.c b/libavcodec/libsvtav1.c
> index 2f5634cee0..73fece49b7 100644
> --- a/libavcodec/libsvtav1.c
> +++ b/libavcodec/libsvtav1.c
> @@ -24,6 +24,7 @@
>  #include <EbSvtAv1ErrorCodes.h>
>  #include <EbSvtAv1Enc.h>
>  
> +#include "libavutil/base64.h"
>  #include "libavutil/common.h"
>  #include "libavutil/frame.h"
>  #include "libavutil/imgutils.h"
> @@ -312,6 +313,22 @@ static int config_enc_params(EbSvtAv1EncConfiguration *param,
>  cpb_props->avg_bitrate = avctx->bit_rate;
>  }
>  
> +    if (avctx->flags & AV_CODEC_FLAG_PASS2) {
> +        if (param->rate_control_mode == SVT_AV1_RC_MODE_VBR) {
> +            if (avctx->flags & AV_CODEC_FLAG_PASS1) {
> +                param->pass = 2;
> +            } else {
> +                param->pass = 3;
> +            }
> +        } else {
> +            param->pass = 2;
> +        }
> +    } else if (avctx->flags & AV_CODEC_FLAG_PASS1) {
> +        param->pass = 1;
> +    } else {
> +        param->pass = 0;
> +    }
> +
>  return 0;
>  }
>  
> @@ -371,6 +388,34 @@ static av_cold int eb_enc_init(AVCodecContext *avctx)
>  return ret;
>  }
>  
> +    if (svt_enc->enc_params.pass >= 2) {
> +        int decode_size;
> +
> +        if (!avctx->stats_in) {
> +            av_log(avctx, AV_LOG_ERROR, "No stats file for %s pass\n",
> +                   svt_enc->enc_params.pass == 2 ? "second" : "third");
> +            return AVERROR_INVALIDDATA;
> +        }
> +
> +        svt_enc->enc_params.rc_stats_buffer.sz = strlen(avctx->stats_in) * 3 / 4;
> +        svt_enc->enc_params.rc_stats_buffer.buf = av_malloc(svt_enc->enc_params.rc_stats_buffer.sz);
> +        if (!svt_enc->enc_params.rc_stats_buffer.buf) {
> +            av_log(avctx, AV_LOG_ERROR,
> +                   "Stat buffer alloc (%"SIZE_SPECIFIER" bytes) failed\n",
> +                   svt_enc->enc_params.rc_stats_buffer.sz);
> +            svt_enc->enc_params.rc_stats_buffer.sz = 0;
> +            return AVERROR(ENOMEM);
> +        }
> +        decode_size = av_base64_decode(svt_enc->enc_params.rc_stats_buffer.buf, avctx->stats_in,
> +                                       svt_enc->enc_params.rc_stats_buffer.sz);
> +        if (decode_size < 0) {
> +            av_log(avctx, AV_LOG_ERROR, "Stat buffer decode failed\n");
> +            return AVERROR_INVALIDDATA;
> +        }
> +
> +        svt_enc->enc_params.rc_stats_buffer.sz = decode_size;
> +    }
> +
>  svt_ret = svt_av1_enc_set_parameter(svt_enc->svt_handle, &svt_enc->enc_params);
>  if (svt_ret != EB_ErrorNone) {
>  return svt_print_error(avctx, svt_ret, "Error setting encoder parameters");
> @@ -544,6 +589,38 @@ static int eb_receive_packet(AVCodecContext *avctx, AVPacket *pkt)
>  if (headerPtr->flags & EB_BUFFERFLAG_EOS)
>  svt_enc->eos_flag = EOS_RECEIVED;
>  
> +    if (svt_enc->eos_flag == EOS_RECEIVED) {
> +        if (svt_enc->enc_params.pass == 1) {
> +            SvtAv1FixedBuf first_pass_stat;
> +            EbErrorType    ret = svt_av1_enc_get_stream_info(
> +                svt_enc->svt_handle,
> +                SVT_AV1_STREAM_INFO_FIRST_PASS_STATS_OUT,
> +                &first_pass_stat);
> +            if (ret == EB_ErrorNone) {
> +                size_t b64_size = AV_BASE64_SIZE(first_pass_stat.sz);
> +                avctx->stats_out = av_malloc(b64_size);
> +                if (!avctx->stats_out) {
> +                    av_log(avctx, AV_LOG_ERROR, "Stat buffer alloc (%"SIZE_SPECIFIER" bytes) failed\n",
> +                           b64_size);
> +                    return AVERROR(ENOMEM);
> +                }
> +                av_base64_encode(avctx->stats_out, b64_size, first_pass_stat.buf,
> +                                 first_pass_stat.sz);
> +            }
> +        }
> +        if (svt_enc->enc_params.pass == 2) {
> +            size_t b64_size = AV_BASE64_SIZE(svt_enc->enc_params.rc_stats_buffer.sz);
> +            avctx->stats_out = av_malloc(b64_size);
> +            if (!avctx->stats_out) {
> +                av_log(avctx, AV_LOG_ERROR, "Stat buffer alloc (%"SIZE_SPECIFIER" bytes) failed\n",
> +                       b64_size);
> +                return AVERROR(ENOMEM);
> +            }
> +            av_base64_encode(avctx->stats_out, b64_size, svt_enc->enc_params.rc_stats_buffer.buf,
> +                             svt_enc->enc_params.rc_stats_buffer.sz);
> +        }
> +    }
> +
>  ff_side_data_set_encoder_stats(pkt, headerPtr->qp * FF_QP2LAMBDA, NULL, 0, pict_type);
>  
>  svt_av1_enc_release_out_buffer(&headerPtr);
> @@ -564,6 +641,11 @@ static av_cold int eb_enc_close(AVCodecContext *avctx)
>  av_freep(&svt_enc->in_buf);
>  }
>  
> +    if (svt_enc->enc_params.rc_stats_buffer.buf) {
> +        av_freep(&svt_enc->enc_params.rc_stats_buffer.buf);
> +        svt_enc->enc_params.rc_stats_buffer.sz = 0;
> +    }
> +
>  av_buffer_pool_uninit(&svt_enc->pool);
>  av_frame_free(&svt_enc->frame); 
>

2-pass doesn't seem to work, the encoder complains it's not the final pass.