ref: ae4f2427e78904f57323f3618f110e2a8b36a602
dir: /aac.c/
#include <u.h>
#include <libc.h>
#include <bio.h>
#include "common.h"
#include "packet.h"
int
aacpacket(Biobuf *out, Packetctx *ctx, Packet *p, int np, uvlong ts)
{
int i, chanc, ratei, objt, sz;
u16int x;
USED(ts);
if(ctx->frid == 0){ /* set up ADTS */
if(ctx->codec.priv.sz < 2){
/* FIXME we could reconstruct it from codec mapping and Audio element */
werrstr("no codec private data to construct ADTS");
return -1;
}
x = ctx->codec.priv.data[0]<<8 | ctx->codec.priv.data[1];
chanc = (x>>3) & 0xf;
ratei = (x>>7) & 0xf;
objt = x>>11;
if(objt > 4){
werrstr("AAC object type %d, can't write ADTS", objt);
return -1;
}
sz = 0; /* will be filled in later */
ctx->adts[0] = 0xff; /* syncword */
ctx->adts[1] = 0xf1; /* syncword, mpeg4, no crc */
ctx->adts[2] = (objt-1)<<6 | ratei<<2 | chanc>>2; /* object type, rate, channel config */
ctx->adts[3] = (chanc&3)<<6 | (sz>>11)&3; /* channel config, frame length */
ctx->adts[4] = sz>>3; /* frame length */
ctx->adts[5] = (sz&7)<<5 | 0x1f; /* frame length, fullness */
ctx->adts[6] = 0xfc; /* fullness, number of frames */
}
for(i = 0; i < np; i++, p++){
sz = 7+p->sz;
ctx->adts[3] = ctx->adts[3]&~3 | (sz>>11)&3; /* channels, frame length */
ctx->adts[4] = sz>>3; /* frame length */
ctx->adts[5] = (sz&7)<<5 | 0x1f; /* frame length, fullness */
if(Bwrite(out, ctx->adts, 7) != 7 || Bwrite(out, p->data, p->sz) != p->sz)
goto err;
}
ctx->frid++;
return 0;
err:
werrstr("aacpacket: %r");
return -1;
}