[MPlayer-users] Incomplete file behaviour

belcampo belcampo at zonnet.nl
Tue Apr 1 12:56:53 CEST 2008

Reimar Döffinger wrote:
> On Tue, Apr 01, 2008 at 12:05:51AM +0200, belcampo wrote:
>> Reimar Döffinger wrote:
>>> On Mon, Mar 31, 2008 at 09:06:00PM +0200, belcampo wrote:
>>>> Reimar Döffinger wrote:
>>>>> On Mon, Mar 31, 2008 at 03:38:15PM +0200, belcampo wrote:
>>>>>> If the contents of a 1000 sec h264 file would be on a distributed 
>>>>>> filesystem, on say a 1000 computers, and 1 would not be available, so 25 
>>>>>> frames would be missing, how would mplayer react on this, hang, or skip 
>>>>>> 1 sec and play the rest of the file ?
>>>>> Sorry, this is too little information to even _guess_. What do you
>>>>> consider a "h264 file"? H.264 Annex B / ES or H.264 in MPEG-TS, or in
>>>>> MPEG-PS or in MOV/MP4?
>>>> MOV/MP4
>>> Since MOV/MP4 _needs_ and index, one missing piece (at beginning or end)
>>> can mean that the file is impossible to play, no matter which player you
>>> use.
>> It's a hinted MP4. I can start playing a remote-file because file-info 
>> is at the beginning
> That doesn't change the fact that if the first part of the file is
> missing it is completely unplayable. MOV/MP4 is the worst format by far to
> use on a unreliable media.
>>>>>   does it just return zeros, random data, or create and I/O error?
>>>> create I/O error
>>> MPlayer will stop playing if it encounters an I/O error. This could be
>>> changed (by changing stream/stream_file.c the fill_buffer function to
>>> e.g. return a buffer filled with all 0 when the read fails), though the
>>> problem is that an I/O error is too little information, how do you know
>>> which is the next part of the file that is available? 
>> I think/hope/believe it will be in the mp4 container
Sorry but I think I answered your question wrong. Bear with me I'm not a 
programmer or otherwise a specialist in networking distributed or not.
What I try to accomplish is to put some things together which will have 
enormous advantages in data-distribution.
I know that a distributed filesystem, pvfs2 btw, is designed as a 
scratch file-system. But it makes some things possible which are 
otherwise impossible/very expensive. I will mirror the distributed 
filesystem to a non-distributed filesystem, so the lacking redundancy 
will be there. I only want to investigate if for whatever reason the 
mirroring/rebuilding doesn't work what will happen then.
And following that what measures could/should I take to overcome that.
The pvfs2 server daemon knows which part of the file is where and should 
know where the rest of the file is.
I hope that I explained what I would like to accomplish and that the 
info is satisfactory. Or would like to receive advice on what I could 
better use then the mp4 container.
> How on earth should the MP4 container know which parts of the file are
> broken due to some computers being offline?? I guess whatever you're
> trying to do is quite feasible, but it is not simple and I think it is
> misusing distributed file systems for something they were never designed
> for.
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