[PD] pix_record -> pix_film plays back too fast

Spencer Russell spencer.f.russell at gmail.com
Tue Aug 5 08:53:49 CEST 2008

Thanks for the Apple Intermediate suggestion, that definitely improved
the situation. It's still having a hard time, though, so I feel like I
must be doing something wrong. A dual core Macbook pro should be able
to encode and store one 640x480 video stream at 20fps no problem,
right? Activity monitor doesn't show my CPU peaking out, but I'm still
getting dropped frames in the recording which cause the playback to be
out of sync, so maybe it's some sort of hard drive throughput problem?

I'll try to put together an example patch of my approach, but this
show opens on Friday, so things are pretty hectic right now and it
might be working "good enough" [sic] that I might focus on some other

Is it generally better to use [auto 1( or a metro for recording using
[pix_record] and playback using [pix_film(, if all I want to do is
record and playback at normal speed with some effects on both ends?

Thanks a bundle,

PS If you're in NYC come see the show! It's called "There Will Be Soft
Rains" and it consists of 3 adaptations of Sci Fi short stories. There
are puppets from the people who did this year's Hamlet in Central
Park, and live sampled-video projection madness running off of PD/GEM!
email me for show dates, etc.

On Mon, Aug 4, 2008 at 4:28 PM, chris clepper <cgclepper at gmail.com> wrote:
> pix_record uses the actual time passed between frames when writing a
> Quicktime file.  This is proven accurate in my testing (probably a million
> files at this point).  One thing you will not get is a perfect 29.97 file
> though.  That requires either offline processing like Final Cut or a
> dedicated clock like a DV cam.
> The more objects running the longer the time between frames, plus the time
> it takes to compress the frame means that it can take a while to record.
> The choice of codec is very important too.  H.264 is not going to work well
> for real time capture, but Apple Intermediate is designed for it.
> On Mon, Aug 4, 2008 at 3:14 PM, Spencer Russell
> <spencer.f.russell at gmail.com> wrote:
>> I'm using pix_record to write processed video captured live from a DV
>> cam to disk, and then playing it back with pix_film. Unfortunately, it
>> seems to record at around 16fps even though GEM should be running at
>> 20. I tried lowering GEM to 15 fps thinking that maybe it was having
>> trouble keeping up, but then it wrote at around 12fps. The framerates
>> are the ones that show up in Quicktime player, and seems to be the
>> same as when I play back with pix_film. I've tried recording both with
>> [auto 1( and banging it with a metro, but strangely it doesn't seem to
>> matter how fast I run the metro. I tried it at 15 fps and 50fps with
>> the gemwin at 20fps and the recorded video seemed to be the same.
>> What controls the framerate of pix_record and pix_film? I'd think that
>> using [auto 1( would do both of them at the GEM rate, but apparently
>> that seems to not be happening.
>> This is on my friend's MacBook pro running OS X.
>> thanks in advance,
>> spencer
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