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

[Colin Ellis]

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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