Re: [xine-devel] seek and input_http

[Xavier H. <xav...@bl...>]

Mike Melanson wrote:

>Xavier Hervy wrote:
>  
>
>>Hi!
>>I'm a bit frustrated this last few days as I would lik to be able to 
>>seek in my http stream.
>>I take a look at the input_http.c file and I should admit that most of 
>>the part is still a big mistery.
>>
>>First of all, http_plugin_seek exist so I was wondering what is the 
>>interst to have this function if the INPUT_CAP_SEEKABLE flag is not set 
>>? this function seems to be never called.
>>Second of all, as I still believe in Santa Clos ;-), I put the seekable 
>>flag but unfortunally it still doesn't work. And xine is not able to 
>>read my stream at all now. It seems that the seek function is called 
>>several times even if I don't try to seek in the stream. In comparison, 
>>the input_file plugin, don't call the seek function as long as the user 
>>don't try to seek ( which seems to be obvious)
>>I decide to replace the http_plugin_seek by:
>>static off_t http_plugin_seek(input_plugin_t *this_gen, off_t offset, 
>>int origin) {
>>  http_input_plugin_t *this = (http_input_plugin_t *) this_gen;
>>  return this->curpos;
>>}
>>
>>now my stream is playable, and the slide bar works in xine-ui.
>>Before I try to implement a new http_plugin_seek function, I like to now:
>>1 what is the purpose of the current function;
>>2 why this function is called hundred times as long as the plugin is 
>>define as seekable?
>>
>>Ty to point me in the good direction
>>    
>>
>
>It is theoretically possible to have an HTTP plugin that can seek
>randomly as if it were reading a file from disk. xine's HTTP plugin does
>not implement this yet. Right now, the plugin just connects to the
>server and asks it to send the whole file over. The plugin consumes the
>data as it comes in. It does have limited seeking capability currently
>in that it can seek forward by discarding bytes until it reaches the
>desired location. It can not presently seek backwards.
>  
>
Even with the fast forward, the seek function is not called.

>There are at least 2 ways to implement random seeking in this case:
>
>1) Save the data to a temporary file on disk and operate on that file
>instead of the network stream.
>  
>
That's what I currently use wget/xine to do this, it might be more a 
frontend implementation...
The advantage with this solution is to be able to seek fully backward 
and partially forward (until the current downloaded file end)
The inconvenient is I haven't always enough free space to save the file 
on the locale system.

>2) Re-architect the whole plugin so that it plays games with the HTTP
>protocol and asks the server to send chunked ranges at a time, rather
>than send the whole file.
>  
>
I just finished a quick and very dirty fix to allow the seeking using 
HTTP protocol. however in my code I don't reuse the previous seeking 
code as I really don't see what he supposed to do.
Xavier