[FFmpeg-devel] [PATCH 13/16] vmdaudio: simplify vmdaudio_decode_frame() by handling block_type first, then making a single call to vmdaudio_loadsound().

[Kostya]

On Tue, Feb 22, 2011 at 02:05:32PM -0500, Justin Ruggles wrote:
> 
> This also adds output buffer size checks for AUDIO and SILENCE block types.
> ---
>  libavcodec/vmdav.c |   24 ++++++++++++------------
>  1 files changed, 12 insertions(+), 12 deletions(-)
> 

> diff --git a/libavcodec/vmdav.c b/libavcodec/vmdav.c
> index 83173d0..92159f6 100644
> --- a/libavcodec/vmdav.c
> +++ b/libavcodec/vmdav.c
> @@ -506,7 +506,7 @@ static int vmdaudio_decode_frame(AVCodecContext *avctx,
>      const uint8_t *buf = avpkt->data;
>      int buf_size = avpkt->size;
>      VmdAudioContext *s = avctx->priv_data;
> -    int block_type;
> +    int block_type, silent_chunks;
>      unsigned char *output_samples = (unsigned char *)data;
>  
>      if (buf_size < 16) {
> @@ -523,23 +523,23 @@ static int vmdaudio_decode_frame(AVCodecContext *avctx,
>      buf      += 16;
>      buf_size -= 16;
>  
> -    if (block_type == BLOCK_TYPE_AUDIO) {
> -        /* the chunk contains audio */
> -        *data_size = vmdaudio_loadsound(s, output_samples, buf, 0, buf_size);
> -    } else if (block_type == BLOCK_TYPE_INITIAL) {
> -        /* initial chunk, may contain audio and silence */
> +    silent_chunks = 0;
> +    if (block_type == BLOCK_TYPE_INITIAL) {
>          uint32_t flags = AV_RB32(buf);
> -        int silent_chunks = av_popcount(flags);
> +        silent_chunks  = av_popcount(flags);
>          buf      += 4;
>          buf_size -= 4;
> -        if(*data_size < (s->block_align*silent_chunks + buf_size) * 2)
> -            return -1;
> -        *data_size = vmdaudio_loadsound(s, output_samples, buf, silent_chunks, buf_size);
>      } else if (block_type == BLOCK_TYPE_SILENCE) {
> -        /* silent chunk */
> -        *data_size = vmdaudio_loadsound(s, output_samples, buf, 1, 0);
> +        silent_chunks = 1;
> +        buf_size = 0; // should already be zero but set it just to be sure
>      }
>  
> +    /* ensure output buffer is large enough */
> +    if (*data_size < (s->block_align*silent_chunks + buf_size) * 2)
> +        return -1;
> +
> +    *data_size = vmdaudio_loadsound(s, output_samples, buf, silent_chunks, buf_size);
> +
>      return avpkt->size;
>  }
>  

will it work if initial block needs to interleave silent and non-silent chunks
in order given by flags?