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vorbisdec: Accept 0 amplitude_bits

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The specification does not prevent an encoder to write the amplitude 0
as 0 amplitude_bits.

Our get_bits() implementation might not support a zero sized read
properly, thus the additional branch.
This commit is contained in:
Luca Barbato 2013-02-24 16:56:15 +01:00
parent 5b47c19bfd
commit 23bd9ef4b2
1 changed files with 3 additions and 7 deletions
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10
libavcodec/vorbisdec.c
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@ -602,13 +602,6 @@ static int vorbis_parse_setup_hdr_floors(vorbis_context *vc)
return AVERROR_INVALIDDATA; return AVERROR_INVALIDDATA;
} }
floor_setup->data.t0.amplitude_bits = get_bits(gb, 6); floor_setup->data.t0.amplitude_bits = get_bits(gb, 6);
/* zero would result in a div by zero later *
* 2^0 - 1 == 0 */
if (!floor_setup->data.t0.amplitude_bits) {
av_log(vc->avccontext, AV_LOG_ERROR,
"Floor 0 amplitude bits is 0.\n");
return AVERROR_INVALIDDATA;
}
floor_setup->data.t0.amplitude_offset = get_bits(gb, 8); floor_setup->data.t0.amplitude_offset = get_bits(gb, 8);
floor_setup->data.t0.num_books = get_bits(gb, 4) + 1; floor_setup->data.t0.num_books = get_bits(gb, 4) + 1;
@ -1059,6 +1052,9 @@ static int vorbis_floor0_decode(vorbis_context *vc,
unsigned amplitude, book_idx; unsigned amplitude, book_idx;
unsigned blockflag = vc->modes[vc->mode_number].blockflag; unsigned blockflag = vc->modes[vc->mode_number].blockflag;
if (!vf->amplitude_bits)
return 1;
amplitude = get_bits(&vc->gb, vf->amplitude_bits); amplitude = get_bits(&vc->gb, vf->amplitude_bits);
if (amplitude > 0) { if (amplitude > 0) {
float last = 0; float last = 0;