[MPlayer-dev-eng] Lots of stuff for NUT

[Oded Shimon]

On Sat, Dec 31, 2005 at 06:37:35PM +0200, Oded Shimon wrote:
> On Sat, Dec 31, 2005 at 04:54:25PM +0100, Michael Niedermayer wrote:
> > do we really need to allow a backptr to point to the current syncpoint? what
> > do we loose if we would point to the previous?
> 
> [...]
> 
> BTW, I'm not sure if it's worth it, but we might want to make 'type' 
> setable by repeat's lsb. In the case of subtitles, you'll have these back 
> ptr's...
> 
> 1 2 3 4 0 0 0 1 2 3 4 5 0 0 0 0 0 ...
> 
> Which is basically bringing out the worst in both methods. I'll investigate 
> this later...

OK, theoretically, we don't need perfect accuracy and having back_ptr point 
different is ok. In practice, it complicates things and makes things more 
unpredictable.

I'm done implmenting the idea I had, and it works perfectly, I'm even a bit
shocked by its low space consumption...

(for 700mb file, 2 streams)
Your index idea:   105220 bytes
My new index idea: 101889 bytes
My new index idea, after throwing away accuracy: 95928

IMO, 6kb is not worth throwing away the accuracy and complicating matters.
BTW, the first 92KB is the syncpoint data, the rest of the 8kb is the 
repeat stuff... So, unless you have 50 audio streams, the inaccuracy thing 
really doesn't matter...

Here's my index idea in detail...

for(i=0; i<stream_count; i++) {
    j = 0;
    while (j < n) {
        repeat = get_s(); // NOTE THE 'S'
        type = (repeat > 0);
        repeat = abs(repeat);
        b = repeat & 1;
        repeat = (repeat >> 1)+1;
        if (type) {
            for(k=0; k<repeat; k++)
                syncpoint[j+k].stream[i].back_ptr = syncpoint[j-b].pos_div8;
        } else {
            for(k=0; k<repeat; k++)
                syncpoint[j+k].stream[i].back_ptr = syncpoint[j+k-b].pos_div8;
        }
        j += repeat;
    }
}

The flaw: 1 and -1 are identical, it's a wasted value. Does anybody care? 
Also I think in a smart muxer, 0 should never be used...

The good: In a very possible scenario of "1 2 3 4 5 0 0 0 0 1 2 3 4 5" in 
subtitles, this code scales perfectly, taking up least space possible.

I vote for this to be official index.

- ods15