diff options
author | Ramiro Polla <ramiro.polla@gmail.com> | 2008-08-17 08:36:06 +0400 |
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committer | Ramiro Polla <ramiro.polla@gmail.com> | 2008-08-17 08:36:06 +0400 |
commit | 6b93147684e53f19680d0f21f0d75b0fa50aec6b (patch) | |
tree | 1750f22544fc38749b5dc9954d124f1f899c2213 /libavcodec/alacenc.c | |
parent | 38c1a5c4d92342b03c718cdbc1e583c49460f684 (diff) |
Import ok'd parts of ALAC encoder from GSoC repo.
Originally committed as revision 14798 to svn://svn.ffmpeg.org/ffmpeg/trunk
Diffstat (limited to 'libavcodec/alacenc.c')
-rw-r--r-- | libavcodec/alacenc.c | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/libavcodec/alacenc.c b/libavcodec/alacenc.c new file mode 100644 index 0000000000..5c6ef0d490 --- /dev/null +++ b/libavcodec/alacenc.c @@ -0,0 +1,197 @@ +/** + * ALAC audio encoder + * Copyright (c) 2008 Jaikrishnan Menon <realityman@gmx.net> + * + * This file is part of FFmpeg. + * + * FFmpeg is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * FFmpeg is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with FFmpeg; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#include "avcodec.h" +#include "bitstream.h" +#include "dsputil.h" +#include "lpc.h" + +#define DEFAULT_FRAME_SIZE 4096 +#define DEFAULT_SAMPLE_SIZE 16 +#define MAX_CHANNELS 8 +#define ALAC_EXTRADATA_SIZE 36 +#define ALAC_FRAME_HEADER_SIZE 55 +#define ALAC_FRAME_FOOTER_SIZE 3 + +#define ALAC_ESCAPE_CODE 0x1FF +#define ALAC_MAX_LPC_ORDER 30 + + int interlacing_shift; + int interlacing_leftweight; + PutBitContext pbctx; + DSPContext dspctx; + AVCodecContext *avctx; +} AlacEncodeContext; + + +static void encode_scalar(AlacEncodeContext *s, int x, int k, int write_sample_size) +{ + int divisor, q, r; + + k = FFMIN(k, s->rc.k_modifier); + divisor = (1<<k) - 1; + q = x / divisor; + r = x % divisor; + + if(q > 8) { + // write escape code and sample value directly + put_bits(&s->pbctx, 9, ALAC_ESCAPE_CODE); + put_bits(&s->pbctx, write_sample_size, x); + } else { + if(q) + put_bits(&s->pbctx, q, (1<<q) - 1); + put_bits(&s->pbctx, 1, 0); + + if(k != 1) { + if(r > 0) + put_bits(&s->pbctx, k, r+1); + else + put_bits(&s->pbctx, k-1, 0); + } + } +} + +static void write_frame_header(AlacEncodeContext *s, int is_verbatim) +{ + put_bits(&s->pbctx, 3, s->channels-1); // No. of channels -1 + put_bits(&s->pbctx, 16, 0); // Seems to be zero + put_bits(&s->pbctx, 1, 1); // Sample count is in the header + put_bits(&s->pbctx, 2, 0); // FIXME: Wasted bytes field + put_bits(&s->pbctx, 1, is_verbatim); // Audio block is verbatim + put_bits(&s->pbctx, 32, s->avctx->frame_size); // No. of samples in the frame +} + +static void write_compressed_frame(AlacEncodeContext *s) +{ + int i, j; + + /* only simple mid/side decorrelation supported as of now */ + alac_stereo_decorrelation(s); + put_bits(&s->pbctx, 8, s->interlacing_shift); + put_bits(&s->pbctx, 8, s->interlacing_leftweight); + + for(i=0;i<s->channels;i++) { + + calc_predictor_params(s, i); + + put_bits(&s->pbctx, 4, 0); // prediction type : currently only type 0 has been RE'd + put_bits(&s->pbctx, 4, s->lpc[i].lpc_quant); + + put_bits(&s->pbctx, 3, s->rc.rice_modifier); + put_bits(&s->pbctx, 5, s->lpc[i].lpc_order); + // predictor coeff. table + for(j=0;j<s->lpc[i].lpc_order;j++) { + put_sbits(&s->pbctx, 16, s->lpc[i].lpc_coeff[j]); + } + } + + // apply lpc and entropy coding to audio samples + + for(i=0;i<s->channels;i++) { + alac_linear_predictor(s, i); + alac_entropy_coder(s); + } +} + +static av_cold int alac_encode_init(AVCodecContext *avctx) +{ + AlacEncodeContext *s = avctx->priv_data; + uint8_t *alac_extradata = av_mallocz(ALAC_EXTRADATA_SIZE+1); + + avctx->frame_size = DEFAULT_FRAME_SIZE; + avctx->bits_per_sample = DEFAULT_SAMPLE_SIZE; + s->channels = avctx->channels; + s->samplerate = avctx->sample_rate; + + if(avctx->sample_fmt != SAMPLE_FMT_S16) { + av_log(avctx, AV_LOG_ERROR, "only pcm_s16 input samples are supported\n"); + return -1; + } + + // Set default compression level + if(avctx->compression_level == FF_COMPRESSION_DEFAULT) + s->compression_level = 1; + else + s->compression_level = av_clip(avctx->compression_level, 0, 1); + + // Initialize default Rice parameters + s->rc.history_mult = 40; + s->rc.initial_history = 10; + s->rc.k_modifier = 14; + s->rc.rice_modifier = 4; + + s->max_coded_frame_size = (ALAC_FRAME_HEADER_SIZE + ALAC_FRAME_FOOTER_SIZE + + avctx->frame_size*s->channels*avctx->bits_per_sample)>>3; + + s->write_sample_size = avctx->bits_per_sample + s->channels - 1; // FIXME: consider wasted_bytes + + AV_WB32(alac_extradata, ALAC_EXTRADATA_SIZE); + AV_WB32(alac_extradata+4, MKBETAG('a','l','a','c')); + AV_WB32(alac_extradata+12, avctx->frame_size); + AV_WB8 (alac_extradata+17, avctx->bits_per_sample); + AV_WB8 (alac_extradata+21, s->channels); + AV_WB32(alac_extradata+24, s->max_coded_frame_size); + AV_WB32(alac_extradata+28, s->samplerate*s->channels*avctx->bits_per_sample); // average bitrate + AV_WB32(alac_extradata+32, s->samplerate); + + // Set relevant extradata fields + if(s->compression_level > 0) { + AV_WB8(alac_extradata+18, s->rc.history_mult); + AV_WB8(alac_extradata+19, s->rc.initial_history); + AV_WB8(alac_extradata+20, s->rc.k_modifier); + } + + avctx->extradata = alac_extradata; + avctx->extradata_size = ALAC_EXTRADATA_SIZE; + + avctx->coded_frame = avcodec_alloc_frame(); + avctx->coded_frame->key_frame = 1; + + s->avctx = avctx; + dsputil_init(&s->dspctx, avctx); + + allocate_sample_buffers(s); + + return 0; +} + +static av_cold int alac_encode_close(AVCodecContext *avctx) +{ + AlacEncodeContext *s = avctx->priv_data; + + av_freep(&avctx->extradata); + avctx->extradata_size = 0; + av_freep(&avctx->coded_frame); + free_sample_buffers(s); + return 0; +} + +AVCodec alac_encoder = { + "alac", + CODEC_TYPE_AUDIO, + CODEC_ID_ALAC, + sizeof(AlacEncodeContext), + alac_encode_init, + alac_encode_frame, + alac_encode_close, + .capabilities = CODEC_CAP_SMALL_LAST_FRAME, + .long_name = "ALAC (Apple Lossless Audio Codec)", +}; |