On 14/11/18 22:39, James Almer wrote: > On 11/14/2018 7:24 PM, Mark Thompson wrote: >> On 11/11/18 02:24, James Almer wrote: >>> Signed-off-by: James Almer <jamr...@gmail.com> >>> --- >>> See https://0x0.st/sljR.webm >>> >>> libavcodec/cbs_av1.c | 30 +++++++++--------------------- >>> 1 file changed, 9 insertions(+), 21 deletions(-) >>> >>> diff --git a/libavcodec/cbs_av1.c b/libavcodec/cbs_av1.c >>> index ff32a6fca5..215f9384e8 100644 >>> --- a/libavcodec/cbs_av1.c >>> +++ b/libavcodec/cbs_av1.c >>> @@ -189,30 +189,26 @@ static int cbs_av1_read_su(CodedBitstreamContext >>> *ctx, GetBitContext *gbc, >>> int width, const char *name, >>> const int *subscripts, int32_t *write_to) >>> { >>> - uint32_t magnitude; >>> - int position, sign; >>> + int position; >>> int32_t value; >>> >>> if (ctx->trace_enable) >>> position = get_bits_count(gbc); >>> >>> - if (get_bits_left(gbc) < width + 1) { >>> + if (get_bits_left(gbc) < width) { >>> av_log(ctx->log_ctx, AV_LOG_ERROR, "Invalid signed value at " >>> "%s: bitstream ended.\n", name); >>> return AVERROR_INVALIDDATA; >>> } >>> >>> - magnitude = get_bits(gbc, width); >>> - sign = get_bits1(gbc); >>> - value = sign ? -(int32_t)magnitude : magnitude; >>> + value = get_sbits(gbc, width); >>> >>> if (ctx->trace_enable) { >>> char bits[33]; >>> int i; >>> for (i = 0; i < width; i++) >>> - bits[i] = magnitude >> (width - i - 1) & 1 ? '1' : '0'; >>> - bits[i] = sign ? '1' : '0'; >>> - bits[i + 1] = 0; >>> + bits[i] = value >> (width - i - 1) & 1 ? '1' : '0'; >> >> Not sure if we care, but right-shifting a negative value is >> implementation-defined. > > Is casting value to unsigned enough, or should i use something like > zero_extend()?
I think using left-shift instead is safe: value & 1 << (...) ? '1' : '0' _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
