[x264-devel] Re: psp specific code?

[Robert Swain]

On 12 Apr 2007, at 20:14, Loren Merritt wrote:
> On Thu, 12 Apr 2007, Paul Canavan wrote:
>> A while ago I hacked a version of mencoder + x264 to produce files  
>> which
>> will play on the PSP (available for download if you search  
>> ps2dev.org). This
>> was based on already publicly available diffs so I didn't actually  
>> do much,
>> just put stuff in the right place. Anyway...
>> [...]
>> Here's what I'd like to do:
>> add a setPSP(int onOff) method, and wrap the psp specific code in  
>> if's. From
>> what I can see, this would result in 3 int comparissons per frame for
>> non-psp users. If this is too much, I could go further by wrapping  
>> the code
>> in #ifdef's (though I always feel that they make code less  
>> readable) and
>> adding a build target.
>
> The standard way to add options is a field in x264_param_t.
>
> But before you continue, is such a patch even needed anymore? iirc  
> recent PSP firmwares don't have gratuitous format restrictions. I  
> won't accept a workaround for something that Sony has already fixed.
> And even aside from that, did PSP compatibility require any changes  
> to the video stream, or only to the MP4 muxing? If it's just  
> muxing, then having support in x264 won't help, because x264  
> doesn't do audio, so you'll have to remux anyway.

As far as I'm aware, PSP firmwares _used_ to require some specific  
MP4 atom, much like the iPod 640x480 'profile' does now though not as  
deeply hidden away. In current times (and I've had this tested by a  
PSP owner running a recent official firmware) this atom is no longer  
required and the only things needed are resolution, profile, level  
etc restrictions that should all be handled outside of x264.

Before anyone jumps in to say 'could iPod 640x480 compatibility be  
added?' there's no real need for that either as it's just a case of  
adding the required atom for iTunes to accept the file for  
synchronisation to the iPod. This can be done with other tools  
(Atomic Parsley). Otherwise just stick to the restrictions and the  
file will be fine. You can even not bother with the atom and use some  
third party software to transfer the files if you like. I've been  
told the iPods themselves are less picky than iTunes.

Rob

PS - <shameless website plug> If you want info on the restrictions  
(and how to encode working files from FFmpeg) you can take a look at:  
http://rob.opendot.cl/index.php/useful-stuff/psp-video-guide/ and  
http://rob.opendot.cl/index.php/useful-stuff/ipod-video-guide/ .  
Feedback is welcome. </shameless website plug>

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