[FFmpeg-devel] [PATCH] libavcodec/ccaption_dec: remove unnecessary buffering of closed caption packets

[Clément Bœsch]

On Fri, Jan 01, 2016 at 04:40:06PM -0800, Aman Gupta wrote:
> From: Aman Gupta <aman at tmm1.net>
> 
> CC data is fed to in small chunks (usually 60 bytes at a time)
> and is parsed fully by the eia608 decoder. There is no reason to copy it
> into a secondary buffer first.
> ---
>  libavcodec/ccaption_dec.c | 22 +---------------------
>  1 file changed, 1 insertion(+), 21 deletions(-)
> 
> diff --git a/libavcodec/ccaption_dec.c b/libavcodec/ccaption_dec.c
> index 9f67caa..4b1d376 100644
> --- a/libavcodec/ccaption_dec.c
> +++ b/libavcodec/ccaption_dec.c
> @@ -167,8 +167,6 @@ typedef struct CCaptionSubContext {
>      int64_t startv_time;
>      int64_t end_time;
>      char prev_cmd[2];
> -    /* buffer to store pkt data */
> -    AVBufferRef *pktbuf;
>  }CCaptionSubContext;
>  
>  
> @@ -185,11 +183,6 @@ static av_cold int init_decoder(AVCodecContext *avctx)
>      if(ret < 0) {
>          return ret;
>      }
> -    /* allocate pkt buffer */
> -    ctx->pktbuf = av_buffer_alloc(128);
> -    if( !ctx->pktbuf) {
> -        ret = AVERROR(ENOMEM);
> -    }
>      return ret;
>  }
>  
> @@ -197,7 +190,6 @@ static av_cold int close_decoder(AVCodecContext *avctx)
>  {
>      CCaptionSubContext *ctx = avctx->priv_data;
>      av_bprint_finalize( &ctx->buffer, NULL);
> -    av_buffer_unref(&ctx->pktbuf);
>      return 0;
>  }
>  
> @@ -524,23 +516,11 @@ static int decode(AVCodecContext *avctx, void *data, int *got_sub, AVPacket *avp
>  {
>      CCaptionSubContext *ctx = avctx->priv_data;
>      AVSubtitle *sub = data;
> -    uint8_t *bptr = NULL;
> +    uint8_t *bptr = avpkt->data;
>      int len = avpkt->size;
>      int ret = 0;
>      int i;
>  
> -    if ( ctx->pktbuf->size < len) {
> -        ret = av_buffer_realloc(&ctx->pktbuf, len);
> -         if(ret < 0) {
> -            av_log(ctx, AV_LOG_WARNING, "Insufficient Memory of %d truncated to %d\n",len, ctx->pktbuf->size);
> -            len = ctx->pktbuf->size;
> -            ret = 0;
> -        }
> -    }
> -    memcpy(ctx->pktbuf->data, avpkt->data, len);
> -    bptr = ctx->pktbuf->data;
> -
> -
>      for (i  = 0; i < len; i += 3) {
>          uint8_t cc_type = *(bptr + i) & 3;
>          if (validate_cc_data_pair( bptr + i) )

This indeed LGTM, but I'm not the maintainer.

-- 
Clément B.
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