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* TTA (The Lossless True Audio) decoder
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* Copyright (c) 2006 Alex Beregszaszi
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* This file is part of FFmpeg.
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* FFmpeg is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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* FFmpeg is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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* You should have received a copy of the GNU Lesser General Public
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* License along with FFmpeg; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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* TTA (The Lossless True Audio) decoder
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* (www.true-audio.com or tta.corecodec.org)
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* @author Alex Beregszaszi
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#define ALT_BITSTREAM_READER_LE
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#define FORMAT_FLOAT 3
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typedef struct TTAFilter {
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int32_t shift, round, error, mode;
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int32_t qm[MAX_ORDER];
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int32_t dx[MAX_ORDER];
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int32_t dl[MAX_ORDER];
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typedef struct TTARice {
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uint32_t k0, k1, sum0, sum1;
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typedef struct TTAChannel {
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typedef struct TTAContext {
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AVCodecContext *avctx;
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int flags, channels, bps, is_float, data_length;
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int frame_length, last_frame_length, total_frames;
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int32_t *decode_buffer;
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static inline int shift_1(int i)
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return 0x80000000; // 16 << 31
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static inline int shift_16(int i)
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return 0x80000000; // 16 << 27
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static const uint32_t shift_1[] = {
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0x00000001, 0x00000002, 0x00000004, 0x00000008,
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0x00000010, 0x00000020, 0x00000040, 0x00000080,
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0x00000100, 0x00000200, 0x00000400, 0x00000800,
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0x00001000, 0x00002000, 0x00004000, 0x00008000,
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0x00010000, 0x00020000, 0x00040000, 0x00080000,
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0x00100000, 0x00200000, 0x00400000, 0x00800000,
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0x01000000, 0x02000000, 0x04000000, 0x08000000,
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0x10000000, 0x20000000, 0x40000000, 0x80000000,
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0x80000000, 0x80000000, 0x80000000, 0x80000000,
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0x80000000, 0x80000000, 0x80000000, 0x80000000
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static const uint32_t * const shift_16 = shift_1 + 4;
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static const int32_t ttafilter_configs[4][2] = {
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static void ttafilter_init(TTAFilter *c, int32_t shift, int32_t mode) {
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memset(c, 0, sizeof(TTAFilter));
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c->round = shift_1[shift-1];
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// c->round = 1 << (shift - 1);
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// FIXME: copy paste from original
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static inline void memshl(register int32_t *a, register int32_t *b) {
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// FIXME: copy paste from original
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// mode=1 encoder, mode=0 decoder
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static inline void ttafilter_process(TTAFilter *c, int32_t *in, int32_t mode) {
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register int32_t *dl = c->dl, *qm = c->qm, *dx = c->dx, sum = c->round;
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sum += *dl++ * *qm, qm++;
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sum += *dl++ * *qm, qm++;
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sum += *dl++ * *qm, qm++;
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sum += *dl++ * *qm, qm++;
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sum += *dl++ * *qm, qm++;
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sum += *dl++ * *qm, qm++;
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sum += *dl++ * *qm, qm++;
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sum += *dl++ * *qm, qm++;
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} else if(c->error < 0) {
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sum += *dl++ * (*qm -= *dx++), qm++;
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sum += *dl++ * (*qm -= *dx++), qm++;
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sum += *dl++ * (*qm -= *dx++), qm++;
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sum += *dl++ * (*qm -= *dx++), qm++;
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sum += *dl++ * (*qm -= *dx++), qm++;
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sum += *dl++ * (*qm -= *dx++), qm++;
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sum += *dl++ * (*qm -= *dx++), qm++;
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sum += *dl++ * (*qm -= *dx++), qm++;
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sum += *dl++ * (*qm += *dx++), qm++;
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sum += *dl++ * (*qm += *dx++), qm++;
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sum += *dl++ * (*qm += *dx++), qm++;
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sum += *dl++ * (*qm += *dx++), qm++;
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sum += *dl++ * (*qm += *dx++), qm++;
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sum += *dl++ * (*qm += *dx++), qm++;
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sum += *dl++ * (*qm += *dx++), qm++;
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sum += *dl++ * (*qm += *dx++), qm++;
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*(dx-0) = ((*(dl-1) >> 30) | 1) << 2;
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*(dx-1) = ((*(dl-2) >> 30) | 1) << 1;
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*(dx-2) = ((*(dl-3) >> 30) | 1) << 1;
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*(dx-3) = ((*(dl-4) >> 30) | 1);
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*in -= (sum >> c->shift);
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*in += (sum >> c->shift);
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*(dl-1) = *dl - *(dl-1);
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*(dl-2) = *(dl-1) - *(dl-2);
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*(dl-3) = *(dl-2) - *(dl-3);
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memshl(c->dl, c->dl + 1);
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memshl(c->dx, c->dx + 1);
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static void rice_init(TTARice *c, uint32_t k0, uint32_t k1)
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c->sum0 = shift_16[k0];
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c->sum1 = shift_16[k1];
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static int tta_get_unary(GetBitContext *gb)
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static av_cold int tta_decode_init(AVCodecContext * avctx)
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TTAContext *s = avctx->priv_data;
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// 30bytes includes a seektable with one frame
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if (avctx->extradata_size < 30)
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init_get_bits(&s->gb, avctx->extradata, avctx->extradata_size);
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if (show_bits_long(&s->gb, 32) == AV_RL32("TTA1"))
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skip_bits(&s->gb, 32);
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// if (get_bits_long(&s->gb, 32) != av_bswap32(AV_RL32("TTA1"))) {
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// av_log(s->avctx, AV_LOG_ERROR, "Missing magic\n");
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s->flags = get_bits(&s->gb, 16);
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if (s->flags != 1 && s->flags != 3)
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av_log(s->avctx, AV_LOG_ERROR, "Invalid flags\n");
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s->is_float = (s->flags == FORMAT_FLOAT);
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avctx->channels = s->channels = get_bits(&s->gb, 16);
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avctx->bits_per_coded_sample = get_bits(&s->gb, 16);
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s->bps = (avctx->bits_per_coded_sample + 7) / 8;
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avctx->sample_rate = get_bits_long(&s->gb, 32);
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if(avctx->sample_rate > 1000000){ //prevent FRAME_TIME * avctx->sample_rate from overflowing and sanity check
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av_log(avctx, AV_LOG_ERROR, "sample_rate too large\n");
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s->data_length = get_bits_long(&s->gb, 32);
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skip_bits(&s->gb, 32); // CRC32 of header
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avctx->sample_fmt = AV_SAMPLE_FMT_FLT;
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av_log(s->avctx, AV_LOG_ERROR, "Unsupported sample format. Please contact the developers.\n");
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else switch(s->bps) {
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// case 1: avctx->sample_fmt = AV_SAMPLE_FMT_U8; break;
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case 2: avctx->sample_fmt = AV_SAMPLE_FMT_S16; break;
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// case 3: avctx->sample_fmt = AV_SAMPLE_FMT_S24; break;
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case 4: avctx->sample_fmt = AV_SAMPLE_FMT_S32; break;
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av_log(s->avctx, AV_LOG_ERROR, "Invalid/unsupported sample format. Please contact the developers.\n");
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// FIXME: horribly broken, but directly from reference source
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#define FRAME_TIME 1.04489795918367346939
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s->frame_length = (int)(FRAME_TIME * avctx->sample_rate);
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s->last_frame_length = s->data_length % s->frame_length;
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s->total_frames = s->data_length / s->frame_length +
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(s->last_frame_length ? 1 : 0);
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av_log(s->avctx, AV_LOG_DEBUG, "flags: %x chans: %d bps: %d rate: %d block: %d\n",
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s->flags, avctx->channels, avctx->bits_per_coded_sample, avctx->sample_rate,
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av_log(s->avctx, AV_LOG_DEBUG, "data_length: %d frame_length: %d last: %d total: %d\n",
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s->data_length, s->frame_length, s->last_frame_length, s->total_frames);
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for (i = 0; i < s->total_frames; i++)
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skip_bits(&s->gb, 32);
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skip_bits(&s->gb, 32); // CRC32 of seektable
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if(s->frame_length >= UINT_MAX / (s->channels * sizeof(int32_t))){
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av_log(avctx, AV_LOG_ERROR, "frame_length too large\n");
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s->decode_buffer = av_mallocz(sizeof(int32_t)*s->frame_length*s->channels);
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s->ch_ctx = av_malloc(avctx->channels * sizeof(*s->ch_ctx));
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return AVERROR(ENOMEM);
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av_log(avctx, AV_LOG_ERROR, "Wrong extradata present\n");
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static int tta_decode_frame(AVCodecContext *avctx,
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void *data, int *data_size,
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const uint8_t *buf = avpkt->data;
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int buf_size = avpkt->size;
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TTAContext *s = avctx->priv_data;
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init_get_bits(&s->gb, buf, buf_size*8);
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int cur_chan = 0, framelen = s->frame_length;
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if (*data_size < (framelen * s->channels * 2)) {
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av_log(avctx, AV_LOG_ERROR, "Output buffer size is too small.\n");
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if (!s->total_frames && s->last_frame_length)
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framelen = s->last_frame_length;
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// init per channel states
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for (i = 0; i < s->channels; i++) {
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s->ch_ctx[i].predictor = 0;
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ttafilter_init(&s->ch_ctx[i].filter, ttafilter_configs[s->bps-1][0], ttafilter_configs[s->bps-1][1]);
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rice_init(&s->ch_ctx[i].rice, 10, 10);
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for (p = s->decode_buffer; p < s->decode_buffer + (framelen * s->channels); p++) {
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int32_t *predictor = &s->ch_ctx[cur_chan].predictor;
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TTAFilter *filter = &s->ch_ctx[cur_chan].filter;
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TTARice *rice = &s->ch_ctx[cur_chan].rice;
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uint32_t unary, depth, k;
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unary = tta_get_unary(&s->gb);
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if (get_bits_left(&s->gb) < k)
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if (k > MIN_CACHE_BITS)
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value = (unary << k) + get_bits(&s->gb, k);
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// FIXME: copy paste from original
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rice->sum1 += value - (rice->sum1 >> 4);
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if (rice->k1 > 0 && rice->sum1 < shift_16[rice->k1])
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else if(rice->sum1 > shift_16[rice->k1 + 1])
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value += shift_1[rice->k0];
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rice->sum0 += value - (rice->sum0 >> 4);
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if (rice->k0 > 0 && rice->sum0 < shift_16[rice->k0])
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else if(rice->sum0 > shift_16[rice->k0 + 1])
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// extract coded value
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#define UNFOLD(x) (((x)&1) ? (++(x)>>1) : (-(x)>>1))
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ttafilter_process(filter, p, 0);
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// fixed order prediction
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#define PRED(x, k) (int32_t)((((uint64_t)x << k) - x) >> k)
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case 1: *p += PRED(*predictor, 4); break;
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case 3: *p += PRED(*predictor, 5); break;
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case 4: *p += *predictor; break;
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// extract 32bit float from last two int samples
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if (s->is_float && ((p - data) & 1)) {
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uint32_t neg = *p & 0x80000000;
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uint32_t hi = *(p - 1);
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uint32_t lo = abs(*p) - 1;
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hi += (hi || lo) ? 0x3f80 : 0;
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// SWAP16: swap all the 16 bits
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*(p - 1) = (hi << 16) | SWAP16(lo) | neg;
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/*if ((get_bits_count(&s->gb)+7)/8 > buf_size)
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av_log(NULL, AV_LOG_INFO, "overread!!\n");
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if (cur_chan < (s->channels-1))
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// decorrelate in case of stereo integer
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if (!s->is_float && (s->channels > 1)) {
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for (*p += *r / 2; r > p - s->channels; r--)
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if (get_bits_left(&s->gb) < 32)
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skip_bits(&s->gb, 32); // frame crc
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// convert to output buffer
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uint16_t *samples = data;
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for (p = s->decode_buffer; p < s->decode_buffer + (framelen * s->channels); p++) {
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// *samples++ = (unsigned char)*p;
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// *samples++ = (unsigned char)(*p >> 8);
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*data_size = (uint8_t *)samples - (uint8_t *)data;
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av_log(s->avctx, AV_LOG_ERROR, "Error, only 16bit samples supported!\n");
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// return get_bits_count(&s->gb)+7)/8;
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static av_cold int tta_decode_close(AVCodecContext *avctx) {
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TTAContext *s = avctx->priv_data;
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if (s->decode_buffer)
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av_free(s->decode_buffer);
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av_freep(&s->ch_ctx);
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AVCodec tta_decoder = {
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.long_name = NULL_IF_CONFIG_SMALL("True Audio (TTA)"),