Re: [PATCH] Small streams and file input plugin

 Hi xine team,
 Hi Miguel,

On Po, 2003-08-04 at 05:15, Miguel Freitas wrote:
> 
> we should separate demuxers that use block read into 3 categories:
> 
> 1) demuxers made to work with block only devices. dvd and cdda should
> fall into that category, they cannot ask data in smaller units because
> the input plugin does not support it.
> 

I agree with this category. Some demuxers have its primary input plugin.

> 2) demuxers that use block read as a convenient way to not have to
> allocate a buf when they know the size to read. in that case, if read
> fails then we probably have an invalid/incomplete file.
> 

Yes, it's reasonable. Demuxers can be simpler - they test only buf == NULL.

> 3) dumb demuxers that know nothing about the stream and are using
> block_read to get something to pass to decoders. i think we only have
> mpeg_elem and mpgaudio here.
> 
> i guess you are trying to fix some problem related to one of demuxers in
> (3), right?. 
> 

Yes, you exactly explain me the problem :-).

> ...so what do you think of reworking mpeg_elem and mpgaudio a bit so
> they don't use block read anymore? :)

Done, finally. See 'block.diff'. I send also patch for gnome_vfs, because it 
should have the same behaviur on end of stream as other input plugins.

There are also problems with non-seekable inputs. In demux_mpgaudio it's send 
some preview data into decoder. For non-seekable input this data aren't played 
and it takes cca 4 seconds! So I recommend change constant NUM_PREVIEW_BUFFERS 
from 10 to 1 (the quickest fix). Is it OK? See 'mp3preview.diff'. 
demux_elem crash (SIGFPE) with non-seekable inputs, also due to preview.

> (hint: you can read up to buf->max_size on every call)
> 

Good idea. I used this:

  blocksize = input_plugin->get_blocksize(...);
   .
   .
  blocksize = (blocksize ? blocksize : buf->max_size);

> regards,
> 
> Miguel
>  
> 
> 

Thanks for advices.
  Frantisek





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block.diff
Description: block.diff

gnome_vfs_read.diff
Description: gnome_vfs_read.diff

mp3preview.diff
Description: mp3preview.diff