[FFmpeg-devel] [PATCH 3/3] avcodec/bitstream: Consistently treat symbol as VLC_TYPE

[Andreas Rheinhardt]

Andreas Rheinhardt:
> If a static VLC table gets initialized a second time (or concurrently by
> two threads) and if said VLC table uses symbols that have the sign bit
> of VLC_TYPE (a typedef for int16_t) set, initializing the VLC fails. The
> reason is that the type of the symbol in the temporary array is an
> uint16_t and so comparing it to the symbol read from the VLC table will
> fail, because only the lower 16bits coincide. Said failure triggers an
> assert.
> 
> Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>
> ---
> Found when playing around a bit with making the ClearVideo VLCs static.
> 
>  libavcodec/bitstream.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libavcodec/bitstream.c b/libavcodec/bitstream.c
> index 39749c6092..a908c10980 100644
> --- a/libavcodec/bitstream.c
> +++ b/libavcodec/bitstream.c
> @@ -129,7 +129,7 @@ static int alloc_table(VLC *vlc, int size, int use_static)
>  
>  typedef struct VLCcode {
>      uint8_t bits;
> -    uint16_t symbol;
> +    VLC_TYPE symbol;
>      /** codeword, with the first bit-to-be-read in the msb
>       * (even if intended for a little-endian bitstream reader) */
>      uint32_t code;
> 
LGTM'ed by Lynne via email and pushed.

- Andreas