static int mpc7_decode_frame(AVCodecContext * avctx, void *data, int *got_frame_ptr, AVPacket *avpkt) { const uint8_t *buf = avpkt->data; int buf_size; MPCContext *c = avctx->priv_data; GetBitContext gb; int i, ch; int mb = -1; Band *bands = c->bands; int off, ret, last_frame, skip; int bits_used, bits_avail; memset(bands, 0, sizeof(*bands) * (c->maxbands + 1)); buf_size = avpkt->size & ~3; if (buf_size <= 0) { av_log(avctx, AV_LOG_ERROR, "packet size is too small (%i bytes)\n", avpkt->size); return AVERROR_INVALIDDATA; } if (buf_size != avpkt->size) { av_log(avctx, AV_LOG_WARNING, "packet size is not a multiple of 4. " "extra bytes at the end will be skipped.\n"); } skip = buf[0]; last_frame = buf[1]; buf += 4; buf_size -= 4; /* get output buffer */ c->frame.nb_samples = last_frame ? c->lastframelen : MPC_FRAME_SIZE; if ((ret = avctx->get_buffer(avctx, &c->frame)) < 0) { av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n"); return ret; } av_fast_padded_malloc(&c->bits, &c->buf_size, buf_size); if (!c->bits) return AVERROR(ENOMEM); c->dsp.bswap_buf((uint32_t *)c->bits, (const uint32_t *)buf, buf_size >> 2); init_get_bits(&gb, c->bits, buf_size * 8); skip_bits_long(&gb, skip); /* read subband indexes */ for(i = 0; i <= c->maxbands; i++){ for(ch = 0; ch < 2; ch++){ int t = 4; if(i) t = get_vlc2(&gb, hdr_vlc.table, MPC7_HDR_BITS, 1) - 5; if(t == 4) bands[i].res[ch] = get_bits(&gb, 4); else bands[i].res[ch] = bands[i-1].res[ch] + t; } if(bands[i].res[0] || bands[i].res[1]){ mb = i; if(c->MSS) bands[i].msf = get_bits1(&gb); } } /* get scale indexes coding method */ for(i = 0; i <= mb; i++) for(ch = 0; ch < 2; ch++) if(bands[i].res[ch]) bands[i].scfi[ch] = get_vlc2(&gb, scfi_vlc.table, MPC7_SCFI_BITS, 1); /* get scale indexes */ for(i = 0; i <= mb; i++){ for(ch = 0; ch < 2; ch++){ if(bands[i].res[ch]){ bands[i].scf_idx[ch][2] = c->oldDSCF[ch][i]; bands[i].scf_idx[ch][0] = get_scale_idx(&gb, bands[i].scf_idx[ch][2]); switch(bands[i].scfi[ch]){ case 0: bands[i].scf_idx[ch][1] = get_scale_idx(&gb, bands[i].scf_idx[ch][0]); bands[i].scf_idx[ch][2] = get_scale_idx(&gb, bands[i].scf_idx[ch][1]); break; case 1: bands[i].scf_idx[ch][1] = get_scale_idx(&gb, bands[i].scf_idx[ch][0]); bands[i].scf_idx[ch][2] = bands[i].scf_idx[ch][1]; break; case 2: bands[i].scf_idx[ch][1] = bands[i].scf_idx[ch][0]; bands[i].scf_idx[ch][2] = get_scale_idx(&gb, bands[i].scf_idx[ch][1]); break; case 3: bands[i].scf_idx[ch][2] = bands[i].scf_idx[ch][1] = bands[i].scf_idx[ch][0]; break; } c->oldDSCF[ch][i] = bands[i].scf_idx[ch][2]; } } } /* get quantizers */ memset(c->Q, 0, sizeof(c->Q)); off = 0; for(i = 0; i < BANDS; i++, off += SAMPLES_PER_BAND) for(ch = 0; ch < 2; ch++) idx_to_quant(c, &gb, bands[i].res[ch], c->Q[ch] + off); ff_mpc_dequantize_and_synth(c, mb, c->frame.data[0], 2); bits_used = get_bits_count(&gb); bits_avail = buf_size * 8; if (!last_frame && ((bits_avail < bits_used) || (bits_used + 32 <= bits_avail))) { av_log(avctx, AV_LOG_ERROR, "Error decoding frame: used %i of %i bits\n", bits_used, bits_avail); return -1; } if(c->frames_to_skip){ c->frames_to_skip--; *got_frame_ptr = 0; return avpkt->size; } *got_frame_ptr = 1; *(AVFrame *)data = c->frame; return avpkt->size; }