[libav-devel] [PATCH 04/14] avcodec/cbs: use a reference to the assembled CodedBitstreamFragment buffer when writing packets

Alexandra Hájková alexandra.khirnova at gmail.com
Mon May 13 10:40:38 CEST 2019


On Sat, May 4, 2019 at 2:15 PM Luca Barbato <lu_zero at gentoo.org> wrote:
>
> From: James Almer <jamrial at gmail.com>
>
> This saves one malloc + memcpy per packet
>
> The CodedBitstreamFragment buffer is padded to follow the requirements
> of AVPacket.
>
> Reviewed-by: jkqxz
> Signed-off-by: James Almer <jamrial at gmail.com>
> ---
>  libavcodec/cbs.c       | 12 ++++++++----
>  libavcodec/cbs_h2645.c |  8 +++++---
>  libavcodec/cbs_mpeg2.c |  3 ++-
>  3 files changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/libavcodec/cbs.c b/libavcodec/cbs.c
> index c5c5b98d24..dc8d94eedc 100644
> --- a/libavcodec/cbs.c
> +++ b/libavcodec/cbs.c
> @@ -321,17 +321,21 @@ int ff_cbs_write_packet(CodedBitstreamContext *ctx,
>                          AVPacket *pkt,
>                          CodedBitstreamFragment *frag)
>  {
> +    AVBufferRef *buf;
>      int err;
>
>      err = ff_cbs_write_fragment_data(ctx, frag);
>      if (err < 0)
>          return err;
>
> -    err = av_new_packet(pkt, frag->data_size);
> -    if (err < 0)
> -        return err;
> +    av_assert0(frag->data_ref);
> +    buf = av_buffer_ref(frag->data_ref);
> +    if (!buf)
> +        return AVERROR(ENOMEM);
>
> -    memcpy(pkt->data, frag->data, frag->data_size);
> +    av_init_packet(pkt);
> +    pkt->buf  = buf;
> +    pkt->data = frag->data;
>      pkt->size = frag->data_size;
>
>      return 0;
> diff --git a/libavcodec/cbs_h2645.c b/libavcodec/cbs_h2645.c
> index d6131a13e5..bf16343db5 100644
> --- a/libavcodec/cbs_h2645.c
> +++ b/libavcodec/cbs_h2645.c
> @@ -1298,7 +1298,7 @@ static int cbs_h2645_assemble_fragment(CodedBitstreamContext *ctx,
>          max_size += 3 + frag->units[i].data_size * 3 / 2;
>      }
>
> -    data = av_malloc(max_size);
> +    data = av_malloc(max_size + AV_INPUT_BUFFER_PADDING_SIZE);
>      if (!data)
>          return AVERROR(ENOMEM);
>
> @@ -1349,11 +1349,13 @@ static int cbs_h2645_assemble_fragment(CodedBitstreamContext *ctx,
>      }
>
>      av_assert0(dp <= max_size);
> -    err = av_reallocp(&data, dp);
> +    err = av_reallocp(&data, dp + AV_INPUT_BUFFER_PADDING_SIZE);
>      if (err)
>          return err;
> +    memset(data + dp, 0, AV_INPUT_BUFFER_PADDING_SIZE);
>
> -    frag->data_ref = av_buffer_create(data, dp, NULL, NULL, 0);
> +    frag->data_ref = av_buffer_create(data, dp + AV_INPUT_BUFFER_PADDING_SIZE,
> +                                      NULL, NULL, 0);
>      if (!frag->data_ref) {
>          av_freep(&data);
>          return AVERROR(ENOMEM);
> diff --git a/libavcodec/cbs_mpeg2.c b/libavcodec/cbs_mpeg2.c
> index 3db10c5152..7fa13c64fa 100644
> --- a/libavcodec/cbs_mpeg2.c
> +++ b/libavcodec/cbs_mpeg2.c
> @@ -369,7 +369,7 @@ static int cbs_mpeg2_assemble_fragment(CodedBitstreamContext *ctx,
>      for (i = 0; i < frag->nb_units; i++)
>          size += 3 + frag->units[i].data_size;
>
> -    frag->data_ref = av_buffer_alloc(size);
> +    frag->data_ref = av_buffer_alloc(size + AV_INPUT_BUFFER_PADDING_SIZE);
>      if (!frag->data_ref)
>          return AVERROR(ENOMEM);
>      data = frag->data_ref->data;
> @@ -388,6 +388,7 @@ static int cbs_mpeg2_assemble_fragment(CodedBitstreamContext *ctx,
>
>      av_assert0(dp == size);
>
> +    memset(data + size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
>      frag->data      = data;
>      frag->data_size = size;
>
> --
> 2.12.2
>

OK


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