flash streaming

Bob Ippolito bob at redivi.com
Mon Oct 9 05:52:56 MSD 2006

On 10/8/06, Jonathan Vanasco <nginx at 2xlp.com> wrote:
> On Oct 8, 2006, at 9:01 PM, Bob Ippolito wrote:
> > No, that's not it. LightHTTPD does not speak the RTMP protocol, it
> > only knows how to seek to a given position in a FLV file given a
> > timecode. People have been doing this for a while, even in PHP.
> wow, thats a dirty hack.

It's not that bad. Basically there's a metadata tag at the beginning
that maps timecodes to offsets in the file. It's on purpose that you
can do this, the FLV file format and the format of streamed FLV are
the same (except FLV files have a signature, and FLV streams are
chunked in some protocol - probably RTMP).

Unfortunately this metadata tag isn't guaranteed to be there and isn't
put there by all of the available tools, hence all the crap about
using flvtool as a post-process in most tutorials.

> > IIRC there's only one open source RTMP server, Red5, but that's only
> > really worthwhile if you're trying to do crap with webcams or
> > microphones, or connect users together (stuff that you would normally
> > use XMLSocket for).
> i thought there were 2 others, but  i can't remember the names.  red5
> was the most mature
> > Proxying would work just fine though. One feature that might
> > facilitate good support for this would be if X-Accel-Redirect accepted
> > an offset... so you could calculate the offset with some scripting
> > language and serve the rest of the file with nginx.
> good idea.
> > Can't it play mp3 files as-is these days?
> last i touched it , one could play an mp3, but not stream/seek.  the
> only way to have a 'scrubber' bar was with flv
> i was using it for online music promotion, so having it in flv was
> useful as a drm measure.  there just aren't any decent media players
> that support flv, and though its easy to convert to mp3 you're really
> just transcoding-- so you can use a marginally better sound quality
> on flv than mp3 and not have to worry about people ripping the cd
> contents from an online album streamer.
> it wasn't drm in the sense of 'this is uncrackable' , but it was drm
> in the sense of 'its not worth your time converting this content' .

Actually most audio in FLV files is MP3... so with a relatively simple
tool you just create mp3 files from the FLV by just extracting the MP3
frames. The other supported audio codecs are either crap (ADPCM) or
proprietary (Nelly Moser), so they're not as common.


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