static int alac_decode_frame(AVCodecContext *avctx, void *outbuffer, int *outputsize, uint8_t *inbuffer, int input_buffer_size) { ALACContext *alac = avctx->priv_data; int channels; int32_t outputsamples; /* short-circuit null buffers */ if (!inbuffer || !input_buffer_size) return input_buffer_size; /* initialize from the extradata */ if (!alac->context_initialized) { if (alac->avctx->extradata_size != ALAC_EXTRADATA_SIZE) { av_log(avctx, AV_LOG_ERROR, "alac: expected %d extradata bytes\n", ALAC_EXTRADATA_SIZE); return input_buffer_size; } alac_set_info(alac); alac->context_initialized = 1; } outputsamples = alac->setinfo_max_samples_per_frame; init_get_bits(&alac->gb, inbuffer, input_buffer_size * 8); channels = get_bits(&alac->gb, 3); *outputsize = outputsamples * alac->bytespersample; switch(channels) { case 0: { /* 1 channel */ int hassize; int isnotcompressed; int readsamplesize; int wasted_bytes; int ricemodifier; /* 2^result = something to do with output waiting. * perhaps matters if we read > 1 frame in a pass? */ get_bits(&alac->gb, 4); get_bits(&alac->gb, 12); /* unknown, skip 12 bits */ hassize = get_bits(&alac->gb, 1); /* the output sample size is stored soon */ wasted_bytes = get_bits(&alac->gb, 2); /* unknown ? */ isnotcompressed = get_bits(&alac->gb, 1); /* whether the frame is compressed */ if (hassize) { /* now read the number of samples, * as a 32bit integer */ outputsamples = get_bits(&alac->gb, 32); *outputsize = outputsamples * alac->bytespersample; } readsamplesize = alac->setinfo_sample_size - (wasted_bytes * 8); if (!isnotcompressed) { /* so it is compressed */ int16_t predictor_coef_table[32]; int predictor_coef_num; int prediction_type; int prediction_quantitization; int i; /* FIXME: skip 16 bits, not sure what they are. seem to be used in * two channel case */ get_bits(&alac->gb, 8); get_bits(&alac->gb, 8); prediction_type = get_bits(&alac->gb, 4); prediction_quantitization = get_bits(&alac->gb, 4); ricemodifier = get_bits(&alac->gb, 3); predictor_coef_num = get_bits(&alac->gb, 5); /* read the predictor table */ for (i = 0; i < predictor_coef_num; i++) { predictor_coef_table[i] = (int16_t)get_bits(&alac->gb, 16); } if (wasted_bytes) { /* these bytes seem to have something to do with * > 2 channel files. */ av_log(avctx, AV_LOG_ERROR, "FIXME: unimplemented, unhandling of wasted_bytes\n"); } bastardized_rice_decompress(alac, alac->predicterror_buffer_a, outputsamples, readsamplesize, alac->setinfo_rice_initialhistory, alac->setinfo_rice_kmodifier, ricemodifier * alac->setinfo_rice_historymult / 4, (1 << alac->setinfo_rice_kmodifier) - 1); if (prediction_type == 0) { /* adaptive fir */ predictor_decompress_fir_adapt(alac->predicterror_buffer_a, alac->outputsamples_buffer_a, outputsamples, readsamplesize, predictor_coef_table, predictor_coef_num, prediction_quantitization); } else { av_log(avctx, AV_LOG_ERROR, "FIXME: unhandled prediction type: %i\n", prediction_type); /* i think the only other prediction type (or perhaps this is just a * boolean?) runs adaptive fir twice.. like: * predictor_decompress_fir_adapt(predictor_error, tempout, ...) * predictor_decompress_fir_adapt(predictor_error, outputsamples ...) * little strange.. */ } } else { /* not compressed, easy case */ if (readsamplesize <= 16) { int i; for (i = 0; i < outputsamples; i++) { int32_t audiobits = get_bits(&alac->gb, readsamplesize); audiobits = SIGN_EXTENDED32(audiobits, readsamplesize); alac->outputsamples_buffer_a[i] = audiobits; } } else { int i; for (i = 0; i < outputsamples; i++) { int32_t audiobits; audiobits = get_bits(&alac->gb, 16); /* special case of sign extension.. * as we'll be ORing the low 16bits into this */ audiobits = audiobits << 16; audiobits = audiobits >> (32 - readsamplesize); audiobits |= get_bits(&alac->gb, readsamplesize - 16); alac->outputsamples_buffer_a[i] = audiobits; } } /* wasted_bytes = 0; // unused */ } switch(alac->setinfo_sample_size) { case 16: { int i; for (i = 0; i < outputsamples; i++) { int16_t sample = alac->outputsamples_buffer_a[i]; ((int16_t*)outbuffer)[i * alac->numchannels] = sample; } break; } case 20: case 24: case 32: av_log(avctx, AV_LOG_ERROR, "FIXME: unimplemented sample size %i\n", alac->setinfo_sample_size); break; default: break; } break; } case 1: { /* 2 channels */ int hassize; int isnotcompressed; int readsamplesize; int wasted_bytes; uint8_t interlacing_shift; uint8_t interlacing_leftweight; /* 2^result = something to do with output waiting. * perhaps matters if we read > 1 frame in a pass? */ get_bits(&alac->gb, 4); get_bits(&alac->gb, 12); /* unknown, skip 12 bits */ hassize = get_bits(&alac->gb, 1); /* the output sample size is stored soon */ wasted_bytes = get_bits(&alac->gb, 2); /* unknown ? */ isnotcompressed = get_bits(&alac->gb, 1); /* whether the frame is compressed */ if (hassize) { /* now read the number of samples, * as a 32bit integer */ outputsamples = get_bits(&alac->gb, 32); *outputsize = outputsamples * alac->bytespersample; } readsamplesize = alac->setinfo_sample_size - (wasted_bytes * 8) + 1; if (!isnotcompressed) { /* compressed */ int16_t predictor_coef_table_a[32]; int predictor_coef_num_a; int prediction_type_a; int prediction_quantitization_a; int ricemodifier_a; int16_t predictor_coef_table_b[32]; int predictor_coef_num_b; int prediction_type_b; int prediction_quantitization_b; int ricemodifier_b; int i; interlacing_shift = get_bits(&alac->gb, 8); interlacing_leftweight = get_bits(&alac->gb, 8); /******** channel 1 ***********/ prediction_type_a = get_bits(&alac->gb, 4); prediction_quantitization_a = get_bits(&alac->gb, 4); ricemodifier_a = get_bits(&alac->gb, 3); predictor_coef_num_a = get_bits(&alac->gb, 5); /* read the predictor table */ for (i = 0; i < predictor_coef_num_a; i++) { predictor_coef_table_a[i] = (int16_t)get_bits(&alac->gb, 16); } /******** channel 2 *********/ prediction_type_b = get_bits(&alac->gb, 4); prediction_quantitization_b = get_bits(&alac->gb, 4); ricemodifier_b = get_bits(&alac->gb, 3); predictor_coef_num_b = get_bits(&alac->gb, 5); /* read the predictor table */ for (i = 0; i < predictor_coef_num_b; i++) { predictor_coef_table_b[i] = (int16_t)get_bits(&alac->gb, 16); } /*********************/ if (wasted_bytes) { /* see mono case */ av_log(avctx, AV_LOG_ERROR, "FIXME: unimplemented, unhandling of wasted_bytes\n"); } /* channel 1 */ bastardized_rice_decompress(alac, alac->predicterror_buffer_a, outputsamples, readsamplesize, alac->setinfo_rice_initialhistory, alac->setinfo_rice_kmodifier, ricemodifier_a * alac->setinfo_rice_historymult / 4, (1 << alac->setinfo_rice_kmodifier) - 1); if (prediction_type_a == 0) { /* adaptive fir */ predictor_decompress_fir_adapt(alac->predicterror_buffer_a, alac->outputsamples_buffer_a, outputsamples, readsamplesize, predictor_coef_table_a, predictor_coef_num_a, prediction_quantitization_a); } else { /* see mono case */ av_log(avctx, AV_LOG_ERROR, "FIXME: unhandled prediction type: %i\n", prediction_type_a); } /* channel 2 */ bastardized_rice_decompress(alac, alac->predicterror_buffer_b, outputsamples, readsamplesize, alac->setinfo_rice_initialhistory, alac->setinfo_rice_kmodifier, ricemodifier_b * alac->setinfo_rice_historymult / 4, (1 << alac->setinfo_rice_kmodifier) - 1); if (prediction_type_b == 0) { /* adaptive fir */ predictor_decompress_fir_adapt(alac->predicterror_buffer_b, alac->outputsamples_buffer_b, outputsamples, readsamplesize, predictor_coef_table_b, predictor_coef_num_b, prediction_quantitization_b); } else { av_log(avctx, AV_LOG_ERROR, "FIXME: unhandled prediction type: %i\n", prediction_type_b); } } else { /* not compressed, easy case */ if (alac->setinfo_sample_size <= 16) { int i; for (i = 0; i < outputsamples; i++) { int32_t audiobits_a, audiobits_b; audiobits_a = get_bits(&alac->gb, alac->setinfo_sample_size); audiobits_b = get_bits(&alac->gb, alac->setinfo_sample_size); audiobits_a = SIGN_EXTENDED32(audiobits_a, alac->setinfo_sample_size); audiobits_b = SIGN_EXTENDED32(audiobits_b, alac->setinfo_sample_size); alac->outputsamples_buffer_a[i] = audiobits_a; alac->outputsamples_buffer_b[i] = audiobits_b; } } else { int i; for (i = 0; i < outputsamples; i++) { int32_t audiobits_a, audiobits_b; audiobits_a = get_bits(&alac->gb, 16); audiobits_a = audiobits_a << 16; audiobits_a = audiobits_a >> (32 - alac->setinfo_sample_size); audiobits_a |= get_bits(&alac->gb, alac->setinfo_sample_size - 16); audiobits_b = get_bits(&alac->gb, 16); audiobits_b = audiobits_b << 16; audiobits_b = audiobits_b >> (32 - alac->setinfo_sample_size); audiobits_b |= get_bits(&alac->gb, alac->setinfo_sample_size - 16); alac->outputsamples_buffer_a[i] = audiobits_a; alac->outputsamples_buffer_b[i] = audiobits_b; } } /* wasted_bytes = 0; */ interlacing_shift = 0; interlacing_leftweight = 0; } switch(alac->setinfo_sample_size) { case 16: { deinterlace_16(alac->outputsamples_buffer_a, alac->outputsamples_buffer_b, (int16_t*)outbuffer, alac->numchannels, outputsamples, interlacing_shift, interlacing_leftweight); break; } case 20: case 24: case 32: av_log(avctx, AV_LOG_ERROR, "FIXME: unimplemented sample size %i\n", alac->setinfo_sample_size); break; default: break; } break; } } return input_buffer_size; }