* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
+#include "libavutil/intreadwrite.h"
#include "libavutil/mathematics.h"
#include "adx.h"
coeff[0] = lrintf(c * 2.0 * (1 << bits));
coeff[1] = lrintf(-(c * c) * (1 << bits));
}
+
+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 <= 0 || 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;
+}