[OpenIndiana-discuss] Comments, please! problem with ffmpeg that seems to be a problem with OI at driver or basic library level

[Hans J. Albertsson]

Yes, running in debug mode seems to make it all work ok, at a slight 
cost in speed.

On 2013-05-15 17:43, Hans J. Albertsson wrote:
> One more piece of test data: upping verbosity one step (pressing '+' 
> in the terminal running ffmpeg) made it all run to completion with 
> minimal time penalty. Worked twice. Will test some more.
>
> That would seem to suggest a buffering/timing issue.
>
>
> On 2013-05-15 17:37, Colin Ellis wrote:
>> I'd suggest trying ffmpeg out with different encodings first to see 
>> if it's
>> stream-specific.  It might actually be libavcodec giving you the hang.
>> I've seen endless loop bugs previously while transcoding audio.
>>
>>
>> On Wed, May 15, 2013 at 8:52 AM, Hans J. Albertsson <
>> hans.j.albertsson at branneriet.se> wrote:
>>
>>> I just discovered that with most Ubuntu versions and recent ffmpegs, 
>>> the
>>> same hang happens there.
>>>
>>> So it isn't just OI.
>>>
>>> Good. Or bad.. Or something. I will look into it, trussing and 
>>> whatever. I
>>> mean my ffmpeg is locally compiled and I have the source code for 
>>> reference.
>>>
>>> On 2013-05-15 16:05, Bob Friesenhahn wrote:
>>>
>>>> On Wed, 15 May 2013, Hans J. Albertsson wrote:
>>>>
>>>>   I regularly download ( quite legally, I'm told ) HLS streams from
>>>>> svtplay.se using ffmpeg and a stream URL obtained by scraping the
>>>>> svtplay.se/<show-link> page.
>>>>>
>>>>> This works very well in Ubuntu and Windows on a separate PC.
>>>>>
>>>>> Under OI and even in W XP inside a VirtualBox VM it hangs, 
>>>>> seemingly at
>>>>> random positions in the stream. The ffmpeg process is totally 
>>>>> inert upon
>>>>> hanging, and one must kill it by two consecutive ^C. It doesn't 
>>>>> respond to
>>>>> the on the fly command language at all.
>>>>>
>>>>> The hang is in pollsys, as demonstrated by the following truss -f 
>>>>> output
>>>>> excerpt from the hanging ffmpeg process.
>>>>>
>>>>> 29961:    pollsys(0x08046768, 1, 0x08046718, 0x00000000)    = 0
>>>>> 29961:    pollsys(0x08046768, 1, 0x08046718, 0x00000000)    = 0
>>>>> 29961:    pollsys(0x08046768, 1, 0x08046718, 0x00000000)    = 0
>>>>> 29961:    pollsys(0x08046768, 1, 0x08046718, 0x00000000)    = 0
>>>>> 29961:    pollsys(0x08046768, 1, 0x08046718, 0x00000000)    = 0
>>>>> 29961:    pollsys(0x08046768, 1, 0x08046718, 0x00000000)    = 0
>>>>> 29961:    pollsys(0x08046768, 1, 0x08046718, 0x00000000)    = 0
>>>>> 29961:    pollsys(0x08046768, 1, 0x08046718, 0x00000000)    = 0
>>>>>
>>>>>
>>>>> I guess that the fact it happens in the W XP in vbox the same as 
>>>>> in OI
>>>>> itself indicates the problem somehow involves code residing under 
>>>>> the Vbox
>>>>> VM, even, and that it's some sort of incompatibility that only will
>>>>> actually have an effect under some sort of race or race-like 
>>>>> condition.
>>>>>
>>>>> I'd appreciate any insight any of you could offer into what this 
>>>>> entails
>>>>>
>>>> I see similar issues with the VLC player which decides that 
>>>> 'mplayer' is
>>>> too slow and not able to keep up.  Without taking time to diagnose, my
>>>> first guess would be a buffering issue which causes the hang.  The 
>>>> software
>>>> is developed under Linux and may have certain buffering (e.g. pipe
>>>> buffering) expectations. Confusion between the buffering and any 
>>>> locking
>>>> (or even just the buffering) might cause a deadlock in the software.
>>>>
>>>> To diagnose, try using 'pstack' on the processes which are hanging and
>>>> see where they are hung.
>>>>
>>>> Bob
>>>>
>>>
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