[vlc-devel] Broken Amazon S3 Streaming

Rémi Denis-Courmont remi at remlab.net
Tue Jun 19 09:13:56 CEST 2012

On Mon, 18 Jun 2012 22:02:20 +0200, Frederic YHUEL <fyhuel at viotech.net>
> IMO, FASTSEEK is not necessary, and it is obviously not possible for a
> *live* DASH or Smooth Streaming stream anyway.

It is necessary. Without FASTSEEK, the demuxer will seek all the time, and
the latency will become so high that playback will stall.

> But maybe I did not understand properly what FASTSEEK means. I guess
> - SEEK is the capability to seek "locally" in the stream within a
> short period of time.
> - FASTSEEK is the capability to seek anywhere in the stream within a
> short period of time.
> Is that right? Is there a more precise definition?

No. That's not right at all.

FASTSEEK means that the byte stream seeking is, well, fast.
SEEK means that seeking is at all possible but may be slow. Then seeking
is acceptable to deal with position change.

Basically, a demuxer can expect seeking to work at all times if FASTSEEK
is set. If only SEEK is set, then seeking should work but may be have too
slow for playback.

Local content is pretty much the only case where FASTSEEK is acceptable.
For HTTP, a new TCP connection and HTTP request/response is required. This
is usually far too slow.

Rémi Denis-Courmont
Sent from my collocated server

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