diff options
Diffstat (limited to 'libavcodec/siren.c')
| -rw-r--r-- | libavcodec/siren.c | 32 |
1 files changed, 31 insertions, 1 deletions
diff --git a/libavcodec/siren.c b/libavcodec/siren.c index 0ecf0fcafc..6909ebbf2e 100644 --- a/libavcodec/siren.c +++ b/libavcodec/siren.c @@ -760,7 +760,37 @@ static int siren_decode(AVCodecContext *avctx, void *data, frame_error = 1; } - skip_bits(gb, s->checksum_bits); + if ((avctx->err_recognition & AV_EF_CRCCHECK) && s->checksum_bits) { + static const uint16_t ChecksumTable[4] = {0x7F80, 0x7878, 0x6666, 0x5555}; + int wpf, checksum, sum, calculated_checksum, temp1; + + checksum = get_bits(gb, s->checksum_bits); + + wpf = bits_per_frame / 16; + sum = 0; + for (int i = 0; i < wpf - 1; i++) + sum ^= AV_RB16(avpkt->data + i * 2) << (i % 15); + sum ^= (AV_RB16(avpkt->data + (wpf - 1) * 2) & ~checksum) << ((wpf - 1) % 15); + sum = (sum >> 15) ^ (sum & 0x7FFF); + + calculated_checksum = 0; + for (int i = 0; i < 4; i++) { + temp1 = ChecksumTable[i] & sum; + + for (int j = 8; j > 0; j >>= 1) + temp1 ^= temp1 >> j; + + calculated_checksum <<= 1; + calculated_checksum |= temp1 & 1; + } + + if (checksum != calculated_checksum) { + av_log(avctx, AV_LOG_WARNING, "Invalid checksum\n"); + if (avctx->err_recognition & AV_EF_EXPLODE) + return AVERROR_INVALIDDATA; + frame_error = 1; + } + } if (frame_error) { memcpy(s->imdct_in, s->backup_frame, number_of_valid_coefs * sizeof(float)); |