[MPlayer-users] Re: lavc-Options for *BEST* quality?

[D Richard Felker III]

On Thu, Feb 13, 2003 at 02:22:47PM +0000, Diego Zuccato wrote:
> [Automatic answer: RTFM (read DOCS, FAQ), also read DOCS/bugreports.html]
> D Richard Felker III wrote:
> 
> > How does such a 'micro-index' help you? You still have to read thru
> > the whole file to seek to a particular time. The only way an index is
> > at all useful is when you can read the whole index at once at the
> > beginning and then have it available for seeking to arbitrary
> > positions.
> It would allow fast "short seeks", like +10sec or -10sec w/o having to
> keep in memory the whole index.
> You can reach the time you want jumping over 2 keyframes at a time (so,
> placing a keyframe every 10 seconds, you can read a disk sector every
> 30s you jump): unlesss your main index is really small, you read LESS
> data from disk this way.

Total data read is irrelevant since the index will only be about 100k
anyway. On the other hand, seeks are very expensive. If I want to seek
90 minutes into a movie, that's 180 seeks times 150 ms/seek (average
for a cdrom) = 27 seconds!! That is total nonsense!!

> IIUC the main AVI index for a 2h movie is about 1M, right? So:
> 2h = 120' => 720keyframes => ~240 sectors gets read (1/3) = ~120k
> Anyway, it's probably slower than reading even 2M if the read is
> continuous, but it would allow seeking in incomplete files.

AVI index is normally like 8-12 megs for 2 hours, IIRC, but AVI is
horribly inefficient.

Anyway seeking is already possible in incomplete files with the MPCF
draft, altho a little more work is required. You have to seek one
packet at a time, not in whole keyframe steps.

Rich