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synced 2024-08-18 23:35:06 +02:00
Import more ok'd parts of ALAC encoder from GSoC repo.
Originally committed as revision 14820 to svn://svn.ffmpeg.org/ffmpeg/trunk
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@ -33,15 +33,52 @@
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#define ALAC_ESCAPE_CODE 0x1FF
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#define ALAC_MAX_LPC_ORDER 30
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#define DEFAULT_MAX_PRED_ORDER 6
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#define DEFAULT_MIN_PRED_ORDER 4
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#define ALAC_MAX_LPC_PRECISION 9
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#define ALAC_MAX_LPC_SHIFT 9
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typedef struct RiceContext {
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int history_mult;
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int initial_history;
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int k_modifier;
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int rice_modifier;
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} RiceContext;
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typedef struct LPCContext {
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int lpc_order;
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int lpc_coeff[ALAC_MAX_LPC_ORDER+1];
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int lpc_quant;
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} LPCContext;
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typedef struct AlacEncodeContext {
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int compression_level;
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int max_coded_frame_size;
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int write_sample_size;
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int32_t sample_buf[MAX_CHANNELS][DEFAULT_FRAME_SIZE];
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int interlacing_shift;
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int interlacing_leftweight;
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PutBitContext pbctx;
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RiceContext rc;
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LPCContext lpc[MAX_CHANNELS];
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DSPContext dspctx;
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AVCodecContext *avctx;
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} AlacEncodeContext;
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static void init_sample_buffers(AlacEncodeContext *s, int16_t *input_samples)
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{
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int ch, i;
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for(ch=0;ch<s->avctx->channels;ch++) {
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int16_t *sptr = input_samples + ch;
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for(i=0;i<s->avctx->frame_size;i++) {
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s->sample_buf[ch][i] = *sptr;
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sptr += s->avctx->channels;
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}
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}
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}
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static void encode_scalar(AlacEncodeContext *s, int x, int k, int write_sample_size)
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{
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int divisor, q, r;
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@ -71,7 +108,7 @@ static void encode_scalar(AlacEncodeContext *s, int x, int k, int write_sample_s
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static void write_frame_header(AlacEncodeContext *s, int is_verbatim)
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{
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put_bits(&s->pbctx, 3, s->channels-1); // No. of channels -1
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put_bits(&s->pbctx, 3, s->avctx->channels-1); // No. of channels -1
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put_bits(&s->pbctx, 16, 0); // Seems to be zero
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put_bits(&s->pbctx, 1, 1); // Sample count is in the header
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put_bits(&s->pbctx, 2, 0); // FIXME: Wasted bytes field
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@ -79,6 +116,38 @@ static void write_frame_header(AlacEncodeContext *s, int is_verbatim)
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put_bits(&s->pbctx, 32, s->avctx->frame_size); // No. of samples in the frame
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}
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static int estimate_stereo_mode(int32_t *left_ch, int32_t *right_ch, int n)
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{
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int i, best;
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int32_t lt, rt;
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uint64_t sum[4];
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uint64_t score[4];
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/* calculate sum of 2nd order residual for each channel */
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sum[0] = sum[1] = sum[2] = sum[3] = 0;
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for(i=2; i<n; i++) {
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lt = left_ch[i] - 2*left_ch[i-1] + left_ch[i-2];
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rt = right_ch[i] - 2*right_ch[i-1] + right_ch[i-2];
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sum[2] += FFABS((lt + rt) >> 1);
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sum[3] += FFABS(lt - rt);
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sum[0] += FFABS(lt);
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sum[1] += FFABS(rt);
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}
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/* calculate score for each mode */
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score[0] = sum[0] + sum[1];
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score[1] = sum[0] + sum[3];
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score[2] = sum[1] + sum[3];
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score[3] = sum[2] + sum[3];
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/* return mode with lowest score */
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best = 0;
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for(i=1; i<4; i++) {
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if(score[i] < score[best]) {
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best = i;
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}
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}
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static void write_compressed_frame(AlacEncodeContext *s)
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{
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int i, j;
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@ -88,7 +157,7 @@ static void write_compressed_frame(AlacEncodeContext *s)
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put_bits(&s->pbctx, 8, s->interlacing_shift);
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put_bits(&s->pbctx, 8, s->interlacing_leftweight);
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for(i=0;i<s->channels;i++) {
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for(i=0;i<s->avctx->channels;i++) {
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calc_predictor_params(s, i);
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@ -105,7 +174,7 @@ static void write_compressed_frame(AlacEncodeContext *s)
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// apply lpc and entropy coding to audio samples
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for(i=0;i<s->channels;i++) {
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for(i=0;i<s->avctx->channels;i++) {
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alac_linear_predictor(s, i);
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alac_entropy_coder(s);
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}
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@ -118,8 +187,6 @@ static av_cold int alac_encode_init(AVCodecContext *avctx)
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avctx->frame_size = DEFAULT_FRAME_SIZE;
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avctx->bits_per_sample = DEFAULT_SAMPLE_SIZE;
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s->channels = avctx->channels;
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s->samplerate = avctx->sample_rate;
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if(avctx->sample_fmt != SAMPLE_FMT_S16) {
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av_log(avctx, AV_LOG_ERROR, "only pcm_s16 input samples are supported\n");
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@ -139,18 +206,18 @@ static av_cold int alac_encode_init(AVCodecContext *avctx)
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s->rc.rice_modifier = 4;
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s->max_coded_frame_size = (ALAC_FRAME_HEADER_SIZE + ALAC_FRAME_FOOTER_SIZE +
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avctx->frame_size*s->channels*avctx->bits_per_sample)>>3;
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avctx->frame_size*avctx->channels*avctx->bits_per_sample)>>3;
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s->write_sample_size = avctx->bits_per_sample + s->channels - 1; // FIXME: consider wasted_bytes
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s->write_sample_size = avctx->bits_per_sample + avctx->channels - 1; // FIXME: consider wasted_bytes
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AV_WB32(alac_extradata, ALAC_EXTRADATA_SIZE);
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AV_WB32(alac_extradata+4, MKBETAG('a','l','a','c'));
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AV_WB32(alac_extradata+12, avctx->frame_size);
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AV_WB8 (alac_extradata+17, avctx->bits_per_sample);
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AV_WB8 (alac_extradata+21, s->channels);
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AV_WB8 (alac_extradata+21, avctx->channels);
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AV_WB32(alac_extradata+24, s->max_coded_frame_size);
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AV_WB32(alac_extradata+28, s->samplerate*s->channels*avctx->bits_per_sample); // average bitrate
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AV_WB32(alac_extradata+32, s->samplerate);
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AV_WB32(alac_extradata+28, avctx->sample_rate*avctx->channels*avctx->bits_per_sample); // average bitrate
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AV_WB32(alac_extradata+32, avctx->sample_rate);
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// Set relevant extradata fields
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if(s->compression_level > 0) {
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@ -168,19 +235,62 @@ static av_cold int alac_encode_init(AVCodecContext *avctx)
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s->avctx = avctx;
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dsputil_init(&s->dspctx, avctx);
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allocate_sample_buffers(s);
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return 0;
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}
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static int alac_encode_frame(AVCodecContext *avctx, uint8_t *frame,
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int buf_size, void *data)
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{
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AlacEncodeContext *s = avctx->priv_data;
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PutBitContext *pb = &s->pbctx;
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int i, out_bytes, verbatim_flag = 0;
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if(avctx->frame_size > DEFAULT_FRAME_SIZE) {
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av_log(avctx, AV_LOG_ERROR, "input frame size exceeded\n");
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return -1;
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}
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if(buf_size < 2*s->max_coded_frame_size) {
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av_log(avctx, AV_LOG_ERROR, "buffer size is too small\n");
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return -1;
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}
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if((s->compression_level == 0) || verbatim_flag) {
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// Verbatim mode
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int16_t *samples = data;
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write_frame_header(s, 1);
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for(i=0; i<avctx->frame_size*avctx->channels; i++) {
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put_sbits(pb, 16, *samples++);
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}
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} else {
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init_sample_buffers(s, data);
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write_frame_header(s, 0);
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write_compressed_frame(s);
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}
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put_bits(pb, 3, 7);
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flush_put_bits(pb);
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out_bytes = put_bits_count(pb) >> 3;
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if(out_bytes > s->max_coded_frame_size) {
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/* frame too large. use verbatim mode */
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if(verbatim_flag || (s->compression_level == 0)) {
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/* still too large. must be an error. */
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av_log(avctx, AV_LOG_ERROR, "error encoding frame\n");
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return -1;
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}
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verbatim_flag = 1;
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goto verbatim;
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}
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return out_bytes;
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}
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static av_cold int alac_encode_close(AVCodecContext *avctx)
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{
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AlacEncodeContext *s = avctx->priv_data;
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av_freep(&avctx->extradata);
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avctx->extradata_size = 0;
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av_freep(&avctx->coded_frame);
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free_sample_buffers(s);
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return 0;
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}
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