// seek to a sample offset relative to the decompressed pcm stream
// returns zero on success, nonzero on failure
private int pcm_seek(long pos)
{
int link = -1;
long total = pcm_total(-1);
if (pos < 0 || pos > total)
{
// goto seek_error;
pcm_offset = -1;
decode_clear();
return(-1);
}
// which bitstream section does this pcm offset occur in?
for (link = links - 1; link >= 0; link--)
{
total -= pcmlengths[link];
if (pos >= total)
{
break;
}
}
// search within the logical bitstream for the page with the highest
// pcm_pos preceeding (or equal to) pos. There is a danger here;
// missing pages or incorrect frame number information in the
// bitstream could make our task impossible. Account for that (it
// would be an error condition)
{
long target = pos - total;
long end = offsets[link + 1];
long begin = offsets[link];
int best = (int)begin;
Page og = new Page();
while (begin < end)
{
long bisect;
int ret;
if (end - begin < CHUNKSIZE)
{
bisect = begin;
}
else
{
bisect = (end + begin) / 2;
}
seek_helper(bisect);
ret = get_next_page(og, end - bisect);
if (ret == -1)
{
end = bisect;
}
else
{
long granulepos = og.granulepos();
if (granulepos < target)
{
best = ret; // raw offset of packet with granulepos
begin = offset; // raw offset of next packet
}
else
{
end = bisect;
}
}
}
// found our page. seek to it (call raw_seek).
if (raw_seek(best) != 0)
{
// goto seek_error;
pcm_offset = -1;
decode_clear();
return(-1);
}
}
// verify result
if (pcm_offset >= pos)
{
// goto seek_error;
pcm_offset = -1;
decode_clear();
return(-1);
}
if (pos > pcm_total(-1))
{
// goto seek_error;
pcm_offset = -1;
decode_clear();
return(-1);
}
// discard samples until we reach the desired position. Crossing a
// logical bitstream boundary with abandon is OK.
while (pcm_offset < pos)
{
float[][] pcm;
int target = (int)(pos - pcm_offset);
float[][][] _pcm = new float[1][][];
int samples = vd.synthesis_pcmout(_pcm, _index);
pcm = _pcm[0];
if (samples > target)
{
samples = target;
}
vd.synthesis_read(samples);
pcm_offset += samples;
if (samples < target)
{
if (process_packet(1) == 0)
{
pcm_offset = pcm_total(-1); // eof
}
}
}
return(0);
// seek_error:
// dump machine so we're in a known state
// pcm_offset=-1;
// decode_clear();
// return -1;
}
