int avpriv_adx_decode_header(AVCodecContext *avctx, const uint8_t *buf, int bufsize, int *header_size, int *coeff) { int offset, cutoff; if (bufsize < 24) return AVERROR_INVALIDDATA; if (AV_RB16(buf) != 0x8000) return AVERROR_INVALIDDATA; offset = AV_RB16(buf + 2) + 4; /* if copyright string is within the provided data, validate it */ if (bufsize >= offset && memcmp(buf + offset - 6, "(c)CRI", 6)) return AVERROR_INVALIDDATA; /* check for encoding=3 block_size=18, sample_size=4 */ if (buf[4] != 3 || buf[5] != 18 || buf[6] != 4) { av_log_ask_for_sample(avctx, "unsupported ADX format\n"); return AVERROR_PATCHWELCOME; } /* channels */ avctx->channels = buf[7]; if (avctx->channels > 2) return AVERROR_INVALIDDATA; /* sample rate */ avctx->sample_rate = AV_RB32(buf + 8); if (avctx->sample_rate < 1 || avctx->sample_rate > INT_MAX / (avctx->channels * BLOCK_SIZE * 8)) return AVERROR_INVALIDDATA; /* bit rate */ avctx->bit_rate = avctx->sample_rate * avctx->channels * BLOCK_SIZE * 8 / BLOCK_SAMPLES; /* LPC coefficients */ if (coeff) { cutoff = AV_RB16(buf + 16); ff_adx_calculate_coeffs(cutoff, avctx->sample_rate, COEFF_BITS, coeff); } *header_size = offset; return 0; }