From d8cec2d7fc1c2c5b6f82b8743b3cfd04cd4bb8cc Mon Sep 17 00:00:00 2001 From: Justin Ruggles Date: Sun, 20 Nov 2011 20:16:05 -0500 Subject: adx: move header decoding to ADX common code --- libavcodec/adx.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 47 insertions(+) (limited to 'libavcodec/adx.c') diff --git a/libavcodec/adx.c b/libavcodec/adx.c index bc3e8825ca..9f03e930be 100644 --- a/libavcodec/adx.c +++ b/libavcodec/adx.c @@ -18,6 +18,7 @@ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ +#include "libavutil/intreadwrite.h" #include "libavutil/mathematics.h" #include "adx.h" @@ -32,3 +33,49 @@ void ff_adx_calculate_coeffs(int cutoff, int sample_rate, int bits, int *coeff) coeff[0] = lrintf(c * 2.0 * (1 << bits)); coeff[1] = lrintf(-(c * c) * (1 << bits)); } + +int ff_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; +} -- cgit v1.2.3