[FFmpeg-devel] [PATCH 3/4] avcodec/filter_units_bsf: Use separate contexts for reading/writing

[Mark Thompson]

On 08/07/2020 02:29, James Almer wrote:
> Based on code from 235a5734e0
> 
> Signed-off-by: James Almer <jamrial at gmail.com>
> ---
>   libavcodec/filter_units_bsf.c | 23 ++++++++++++++---------
>   1 file changed, 14 insertions(+), 9 deletions(-)
> 
> diff --git a/libavcodec/filter_units_bsf.c b/libavcodec/filter_units_bsf.c
> index 354594ac50..14960761d2 100644
> --- a/libavcodec/filter_units_bsf.c
> +++ b/libavcodec/filter_units_bsf.c
> @@ -29,7 +29,8 @@
>   typedef struct FilterUnitsContext {
>       const AVClass *class;
>   
> -    CodedBitstreamContext *cbc;
> +    CodedBitstreamContext *input;
> +    CodedBitstreamContext *output;
>       CodedBitstreamFragment fragment;
>   
>       const char *pass_types;
> @@ -112,7 +113,7 @@ static int filter_units_filter(AVBSFContext *bsf, AVPacket *pkt)
>       if (ctx->mode == NOOP)
>           return 0;
>   
> -    err = ff_cbs_read_packet(ctx->cbc, frag, pkt);
> +    err = ff_cbs_read_packet(ctx->input, frag, pkt);
>       if (err < 0) {
>           av_log(bsf, AV_LOG_ERROR, "Failed to read packet.\n");
>           goto fail;
> @@ -134,7 +135,7 @@ static int filter_units_filter(AVBSFContext *bsf, AVPacket *pkt)
>           goto fail;
>       }
>   
> -    err = ff_cbs_write_packet(ctx->cbc, pkt, frag);
> +    err = ff_cbs_write_packet(ctx->output, pkt, frag);
>       if (err < 0) {
>           av_log(bsf, AV_LOG_ERROR, "Failed to write packet.\n");
>           goto fail;
> @@ -179,22 +180,25 @@ static int filter_units_init(AVBSFContext *bsf)
>           return 0;
>       }
>   
> -    err = ff_cbs_init(&ctx->cbc, bsf->par_in->codec_id, bsf);
> +    err = ff_cbs_init(&ctx->input, bsf->par_in->codec_id, bsf);
> +    if (err < 0)
> +        return err;
> +    err = ff_cbs_init(&ctx->output, bsf->par_in->codec_id, bsf);
>       if (err < 0)
>           return err;
>   
>       // Don't actually decompose anything, we only want the unit data.
> -    ctx->cbc->decompose_unit_types    = ctx->type_list;
> -    ctx->cbc->nb_decompose_unit_types = 0;
> +    ctx->input->decompose_unit_types    = ctx->type_list;
> +    ctx->input->nb_decompose_unit_types = 0;
>   
>       if (bsf->par_in->extradata) {
>           CodedBitstreamFragment *frag = &ctx->fragment;
>   
> -        err = ff_cbs_read_extradata(ctx->cbc, frag, bsf->par_in);
> +        err = ff_cbs_read_extradata(ctx->input, frag, bsf->par_in);
>           if (err < 0) {
>               av_log(bsf, AV_LOG_ERROR, "Failed to read extradata.\n");
>           } else {
> -            err = ff_cbs_write_extradata(ctx->cbc, bsf->par_out, frag);
> +            err = ff_cbs_write_extradata(ctx->output, bsf->par_out, frag);
>               if (err < 0)
>                   av_log(bsf, AV_LOG_ERROR, "Failed to write extradata.\n");
>           }
> @@ -212,7 +216,8 @@ static void filter_units_close(AVBSFContext *bsf)
>       av_freep(&ctx->type_list);
>   
>       ff_cbs_fragment_free(&ctx->fragment);
> -    ff_cbs_close(&ctx->cbc);
> +    ff_cbs_close(&ctx->input);
> +    ff_cbs_close(&ctx->output);
>   }
>   
>   #define OFFSET(x) offsetof(FilterUnitsContext, x)
> 

Given that it never decomposes anything, I don't think that has any effect?  Possibly it's a good idea to be consistent anyway - I don't really mind.

The other three patches in this series look right to me in any case.

Thanks,

- Mark