[GEM-dev] gem framerate acuracy

B. Bogart ben at ekran.org
Sat May 19 23:50:37 CEST 2007


Hi Cyrille,

Sounds like your skipping frames which is like seeking, and then any
codec with inter-frame compression will suck, much harder for the
machine to calculate each 10th frame.

Did you try photo-jpeg as suggested by others?

Try shark, I found it very useful to find stupid CPU usage issues that
were related to quicktime and not Gem in the past, so give it a try and
see what function is using the most CPU... could be a hint.

B.

cyrille henry wrote:
> 
> Roman Haefeli a écrit :
>> On Sat, 2007-05-19 at 17:19 +0200, cyrille henry wrote:
>>> hello,
>>>
>>> chris clepper a écrit :
>>>> On 5/15/07, cyrille henry <cyrille.henry at la-kitchen.fr> wrote:
>>>>> i used the gemhead to trigger the counter.
>>>>>
>>>>> i just insert a delay 5 in order to to trig the counter between 2 frame.
>>>>> it look better.
>>>>> is it possible, or it's just because i'm fade up looking for the same
>>>>> movie everytime?
>>>> Maybe you were seeing some differences between the metro driven counter and
>>>> the GEM render cycle?  Keep in mind these objects use Pd's logical time
>>>> which is in no way consistent with actual real world time.
>>> i think we where just tired. 
>>>
>>> i'm still tring to find a solution. i don't have the computer with me anymore, so testing is not really easy.
>>>
>>> if the hard drive is a limiting factor, maybe i can use someting faster to store the movie.
>>> a fast usbflash could be faster (osx monitor tells me that the i read the HD at maximum 4Mb/s, while fast flash usbstick can be read at 30 Mb/s).
>>>
>>>
>>> the other solution i can imagine is to use the time object in order to get the time beween 2 frame, and compute the frame number i should get. this will not reduce the glitchs, but at last the velocity of the movy should be constant.
>>>
>>>
>>> does anyone already tried one of this "solution"?
>> i still believe, the best solution would be to set the framerate to the
>> movie's native framerate and then use a counter,
> well, the movie playback framerate change. mostly for 1 to 10, but can go thrus 0.1 to 50 or 100 for short period of time
> 
>> that is triggered by
>> [gemhead], to choose the frame.
> 
> i already use some kind of counter to play the movie.
> 
>> if cpu and hd are fast enough, you'll
>> get a tight playback.
> unfortunatly, i din't have a tight playback. specially when playback speed is high.
> 
>> if one or the other is too slow, this approach
>> won't help, of course, and the movie is played back too slow. the
>> question is, what does have more priority for you: playing every frame
>> or keeping the original velocity.
> i don't play every frame (when playback speed is > 1).
> i don't keep the original velocity ether.
> i just whant something that look smooth, 
> that's not the case mostly because time between every frame is not constant.
> 
> 
> thanks
> Cyrille
> 
>> roman
>>
>>  
>>
>>> thanks for the help
>>> Cyrille
>>>
>>>> The 'rate' message exists because it allows Quicktime to do all of the
>>>> timing for when to get frames.  Pd's logical time cannot be used for this
>>>> efficiently or accurately.  pix_movie/film attempts to make the Quicktime
>>>> timing work with Pd's time but it is not always effective.
>>>>
>>> chris clepper a écrit :
>>>> On 5/15/07, cyrille henry <cyrille.henry at la-kitchen.fr> wrote:
>>>>> i used the gemhead to trigger the counter.
>>>>>
>>>>> i just insert a delay 5 in order to to trig the counter between 2 frame.
>>>>> it look better.
>>>>> is it possible, or it's just because i'm fade up looking for the same
>>>>> movie everytime?
>>>> Maybe you were seeing some differences between the metro driven counter and
>>>> the GEM render cycle?  Keep in mind these objects use Pd's logical time
>>>> which is in no way consistent with actual real world time.
>>>>
>>>> The 'rate' message exists because it allows Quicktime to do all of the
>>>> timing for when to get frames.  Pd's logical time cannot be used for this
>>>> efficiently or accurately.  pix_movie/film attempts to make the Quicktime
>>>> timing work with Pd's time but it is not always effective.
>>>>
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>>
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