Enabling gzip

dinkypumpkin dinkypumpkin at gmail.com
Wed Jun 13 18:20:33 EDT 2012

On 13/06/2012 21:18, Arthur Murray wrote:
> I was wondering what stco parsing is and if gzip should really still
> be disabled by default?  The commented out line was added in 2009.
> I'd prefer to enable it to reduce download times and wasted internet
> bytes, and would prefer to solve the real problem if there is one. How
> can I test if this mystery "perl bug" still exists or if there is any
> downside to enabling it now in 2012? I've briefly tested while gzip
> was enabled and I didn't notice any problems.
> 1921         # Using this slows down stco parsing!!
> 1922         #$ua->default_header( 'Accept-Encoding', 'gzip,deflate' );
> ...
> 2522         # Only return decoded content if gzip is used - otherwise
> this severely slows down stco scanning! Perl bug?

I presume that "stco parsing" refers to accessing iPhone streams, 
something get_iplayer used to do.  The "stco" atom in an MP4 container 
holds a lookup table for the actual data chunks in the file, for 
seeking, etc.  I can see how adding overhead for decompression could 
slow things down.  That iPhone-related code is still in get_iplayer, but 
it's deadwood since the BBC locked down the iPhone streams a couple of 
years ago.  These days the only things get_iplayer itself downloads are 
XML resources of one sort or another.  rtmpdump (and mplayer for WMA) 
handle all the streaming now.  I don't know if enabling that 
Accept-Encoding header will make much of a difference.  If you can 
quantify a significant speed-up with it, by all means submit a patch.  I 
would guess the best place to test timings is when doing full refreshes 
of the cache.

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