static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame_ptr, AVPacket *pkt) { GetBitContext gb; VimaContext *vima = avctx->priv_data; int16_t pcm_data[2]; uint32_t samples; int8_t channel_hint[2]; int ret, chan, channels = 1; init_get_bits(&gb, pkt->data, pkt->size * 8); if (pkt->size < 13) return AVERROR_INVALIDDATA; samples = get_bits_long(&gb, 32); if (samples == 0xffffffff) { skip_bits_long(&gb, 32); samples = get_bits_long(&gb, 32); } if (samples > pkt->size * 2) return AVERROR_INVALIDDATA; channel_hint[0] = get_sbits(&gb, 8); if (channel_hint[0] & 0x80) { channel_hint[0] = ~channel_hint[0]; channels = 2; } avctx->channels = channels; avctx->channel_layout = (channels == 2) ? AV_CH_LAYOUT_STEREO : AV_CH_LAYOUT_MONO; pcm_data[0] = get_sbits(&gb, 16); if (channels > 1) { channel_hint[1] = get_sbits(&gb, 8); pcm_data[1] = get_sbits(&gb, 16); } vima->frame.nb_samples = samples; if ((ret = avctx->get_buffer(avctx, &vima->frame)) < 0) { av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n"); return ret; } for (chan = 0; chan < channels; chan++) { uint16_t *dest = (uint16_t*)vima->frame.data[0] + chan; int step_index = channel_hint[chan]; int output = pcm_data[chan]; int sample; for (sample = 0; sample < samples; sample++) { int lookup_size, lookup, highbit, lowbits; step_index = av_clip(step_index, 0, 88); lookup_size = size_table[step_index]; lookup = get_bits(&gb, lookup_size); highbit = 1 << (lookup_size - 1); lowbits = highbit - 1; if (lookup & highbit) lookup ^= highbit; else highbit = 0; if (lookup == lowbits) { output = get_sbits(&gb, 16); } else { int predict_index, diff; predict_index = (lookup << (7 - lookup_size)) | (step_index << 6); predict_index = av_clip(predict_index, 0, 5785); diff = vima->predict_table[predict_index]; if (lookup) diff += ff_adpcm_step_table[step_index] >> (lookup_size - 1); if (highbit) diff = -diff; output = av_clip_int16(output + diff); } *dest = output; dest += channels; step_index += step_index_tables[lookup_size - 2][lookup]; } } *got_frame_ptr = 1; *(AVFrame *)data = vima->frame; return pkt->size; }