if(op->packetno < 3) { if(vorbis_synthesis_headerin(&context->vi, &context->vc, op)<0){ av_log(avccontext, AV_LOG_ERROR, "%lld. vorbis header damaged\n", op->packetno+1); return -1; } avccontext->channels = context->vi.channels ; avccontext->sample_rate = context->vi.rate ; op->packetno++; return buf_size ; }  if(op->packetno == 3) {    vorbis_synthesis_init(&context->vd, &context->vi) ; vorbis_block_init(&context->vd, &context->vb); }
static int oggvorbis_decode_frame(AVCodecContext *avccontext,                        void *data, int *data_size,                        uint8_t *buf, int buf_size){    OggVorbisContext *context = avccontext->priv_data ;    float **pcm ;    ogg_packet *op= &context->op;        int samples, total_samples, total_bytes,i;     if(!buf_size){    //FIXME flush        *data_size=0;        return 0;    }        op->packet = buf;    op->bytes  = buf_size;    op->b_o_s  = op->packetno == 0;//    av_log(avccontext, AV_LOG_DEBUG, "%d %d %d %lld %lld %d %d\n", op->bytes, op->b_o_s, op->e_o_s, op->granulepos, op->packetno, buf_size, context->vi.rate);    /*    for(i=0; i<op->bytes; i++)      av_log(avccontext, AV_LOG_DEBUG, "%02X ", op->packet[i]);    av_log(avccontext, AV_LOG_DEBUG, "\n");*/    if(op->packetno < 3) {	if(vorbis_synthesis_headerin(&context->vi, &context->vc, op)<0){            av_log(avccontext, AV_LOG_ERROR, "%lld. vorbis header damaged\n", op->packetno+1);            return -1;        }	avccontext->channels = context->vi.channels ;	avccontext->sample_rate = context->vi.rate ;        op->packetno++;	return buf_size ;    }    if(op->packetno == 3) {//	av_log(avccontext, AV_LOG_INFO, "vorbis_decode: %d channel, %ldHz, encoder `%s'\n",//		context->vi.channels, context->vi.rate, context->vc.vendor);	vorbis_synthesis_init(&context->vd, &context->vi) ;	vorbis_block_init(&context->vd, &context->vb);     }    if(vorbis_synthesis(&context->vb, op) == 0)	vorbis_synthesis_blockin(&context->vd, &context->vb) ;        total_samples = 0 ;    total_bytes = 0 ;    while((samples = vorbis_synthesis_pcmout(&context->vd, &pcm)) > 0) {	conv(samples, pcm, (char*)data + total_bytes, context->vi.channels) ;	total_bytes += samples * 2 * context->vi.channels ;	total_samples += samples ;        vorbis_synthesis_read(&context->vd, samples) ;    }    op->packetno++;    *data_size = total_bytes ;       return buf_size ;}