Converting MP4 video for the PSP (h264/AVC) on Linux

After my earlier post about converting video for the PSP proved to be pretty popular, I decided to do a new, easier, better and improved guide. Well, here it is, as promised. It took me a while because I had a lot of other things on my head the last few months. Well, better late then never, so they say. This time we're going to do MPEG-4 AVC (aka H.264) instead of plain old MPEG-4 ASP I used in the last post. A lot of things have happened since I wrote that other guide more than a year ago. First of all, I've learned a lot more about the PSP's compression techniques, mostly thanks to Robert Swain's great blog. Secondly, newer firmwares released by Sony have loosened up the restrictions for Video on the PSP. So first I'll show you a updated list of the restrictions for video on the PSP in AVC (AFAIK):

• MPEG-4 File Format
• MPEG-4 AVC Video codec
• H.264 Main Profile up to Level 3.0
• Any framerate up to 30 fps
• Up to 2 reference frames
• Arithmetic Coding (CABAC)
• Width/Height must be a multiple of 16
• Allowed Resolutions:
• Any resolution up to 320x240
• 352x240 (VCD)
• 352x480 (CVD)
• 480x272 (Native)
• 720x480 (DVD)
• No 8x8 transform
• No reference b-frames
• MPEG-4 AAC Audio codec
• 48000 kHz

We no longer have to use the command-line tool ffmpeg, thanks to a great piece of software called Avidemux. If you're using Ubuntu 8.04 LTS, Avidemux 2.4.1 comes in the repository so all you have to do is install the 'avidemux' pakage through your prefered method. Older versions of Ubuntu come with Avidemux 2.3 which, unfortunately, can't handle the PSP format properly. So in that case I recommend you to go over at GetDeb and download an Ubuntu package of the latest version of Avidemux there. If you're not using Ubuntu, check http://fixounet.free.fr/avidemux/download.html to see if there are any packages of Avidemux 2.4 or higher for your Linux distribution. To install the package in Ubuntu, just double-click it and let gdebi do the rest. Another tool that can help a lot when working with video, and a great video player in general, is mplayer. In Ubuntu you can install it from the repository. (sudo apt-get install mplayer) After installing Avidemux, run it. In Ubuntu it should be in the [Applications]->[Audio & Video] menu. Avidemux' interface is pretty straightforward. The first step is to load the video that you want to convert. To do that just click the [Open] button in the toolbar, select your video and click Ok. It is possible Avidemux will ask you whether you want to index or rebuild the frames for you video. Just click Yes and let it do it's work. After opening your video, you can play it and browse trough it like any other media player. Now let's convert this video! Avidemux comes with a preset that will automatically configure it to convert to PSP-compatible video. All you have to do is go to the [Auto] menu and select [PSP (H.264)]. Then a little dialog window will show up. Target type can be PSP 480*272 or PSP full res (720x480). Full res is only really useful if you have a PSP Slim and want to play your movie on TV through the Video-out cable. (The PSP's native resolution is 480x272, while standard NTSC resolution is 720x480.) Converting at the higher resolution will, as you probably know or guessed, result in a bigger file. (Around 700 MB for a whole movie vs. 400 MB for a movie at lower resolution.) If you know the aspect ratio of your movie you can configure this as well. If you don't, just leave both at 1:1. After confirming this dialog, if you're in a hurry, you could just click Save, choose a destination and Avidemux would produce a file that's perfectly playable on your PSP. However, the default encoder options used by Avidemux will produce large files with comparably lower quality, so I really recommend you go through this guide. Also, you might want to take a look at the filters to make sure the video will look exactly the way you want it to. First let's optimize the codec options. Click on [Configure] on the left panel under the Video codec dropdown box. The first and probably most important step in improving the encoding quality and reduce size is to change the Encoding Mode from One Pass to Two Pass. This will make Avidemux encode the video two times, the first pass serves to analyse the video for scene changes etc. so it can encode the video more efficiently in the second pass. If you are encoding for 480x272 resolution, set the bitrate to 384 kbit/s, that will be plenty with all optimizations enabled. If you are going for full res (720x480) you should choose a higher resolution, like 632 kbit/s 768 kbit/s. Now go through all the tabs and set the options exactly like you see them in the pictures below. I'm not going to explain what every option does, but just trust me when I say that this will configure the encoder for super-mega-uber-optimized encoding. The Motion & Misc tab. The Partitions & Frames tab. The only changes on the Rate Control tab are Scene Cut Threshold: 40 and Max IDR frame interval: 300 You don't have to change anything on the More tab, just click OK now. After this tedious process it is a good idea to save the current configuration as a project, so you don't have to open up this page every time you decide to encode some videos. Click [File]->[Save Project]. Avidemux doesn't dictate any file extension, but for your own sanity it might be a good idea to make up one of your own. I just tend to call them 'foo.project'. (Yes, not very creative, I know.) Now that you have saved the current project, whatever happens, you won't have to go and configure all those settings again. You can open projects through [File]->[Load/Run Project...]. One of the coolest things of Avidemux (well, at least for videophiles like me) is the ease with which you can configure filters. In the main Avidemux window click on [Filters] under the Video section on the sidebar and the Video Filter Manager will pop-up, it looks something like this. On the left you see all available filters, on the right you see the filters currently applied to the video. Now Avidemux tries to act somewhat intelligent when you choose an 'auto'-preset. Basicly it will resize the video so it fits in the PSP's resolution, and then add black borders to fill up the remaining space. That means that if your movie is too wide (like the cinematic 2.35:1 aspect), it will add black borders above and under the video. If it's too narrow (like good ol' 4:3 video) it will add borders left and right. However if your video uses a non-square pixel (anamorphic) resolution, your video might get deformed on the PSP if Avidemux can't figure out what the correct aspect of the source video should be. If you want to know if the video is anamorphic, open it with mplayer from the command line. Look out for a line containing something like 720x480 => 853x480. If the resolution is adjusted, (it shows to different resolutions) the video is anamorphic. (NOTE: if you have a widescreen monitor you have to edit /etc/mplayer/mplayer.conf and add/change the option "aspect = 16:10", assuming your monitor's aspect ratio is 16:10. Otherwise mplayer will assume your monitor is 4:3 and adjust all videos correspondingly.) Another problem is that when a video is allready letterboxed (ie. a widescreen movie that allready contains black borders), Avidemux will still add borders left and right, resulting in black borders all around the video. I will handle 2 different use cases here to help you understand everything better. Anamorphic Video This is most common with downloaded music clips, older television shows, etc. I found out I got an anamorphic video by playing it with mplayer from the command line first, one of the lines it outputted on the terminal was: VO: [xv] 352x240 => 352x270 Planar YV12 The resolution of this vid is 352x240, but it is in fact in 4:3 perspective. Mplayer figured this out and automatically adjusted the resolution. Actually, I could allready have guessed it was anamorphic by just looking at the video in any video player, see it was a normal 4:3 video, and noting that the resolution is not 4:3. (352/4*3 = 264) Now Avidemux's isn't as smart as mplayer, and will think the vid is 352x240 with square pixels. The PSP preset will just resize it in the same preset so that it fits, and then add black borders. First of all, with 4:3 video black borders aren't necessary at all, and just make the video bigger, so first we remove the 'Add black borders' filter (just select the filter and click the minus button). Now we change the MPlayer resize filter (select the filter, click configure) so that it resizes the video to a 4:3 resolution. It might seem logical to just resize it to 352x264 but there's one detail: 264 isn't dividable by 16, so the PSP won't play it. Instead it's better to just resize 4:3 video to 320x240 (it's the highest real 4:3 resolution that will cleanly divide and fits in the PSP's native resolution). Cropping Widescreen Video Ok, so now we have a movie in it's original 2.35:1 widescreen format. The PSP prefix will just resize it to 480 x something and then add borders. If you want the video to be in it's original form, without any cropping, that's okay. However, the PSP's screen isn't a 42" TV. So it's sometimes a good idea to crop the movie so it will fit optimally on your PSP's display. Figure out the videos resolution before going to the filters. (You can find out everything about a video inside Avidemux by clicking the little properties button.) The first step is to remove the black borders filter, the resize filter and any other filters. Then you add a crop filter. Now you need to do some math. For example, my video is 620x256. I want to crop it to 16:9, so I do 256 / 9 * 16 = 455.111. So the cropped size is going to be 455x256. That means I need to crop a total of 620 - 455.111 = 164.889. Divide that by 2 and you get 82,44. In other words, I crop 83 pixels from one side and 82 pixels from the other. After you have applied the crop filter, all that is left is to resize the movie to the proper 480x272 resolution. Anyway, whenever you're happy with your settings all you need to do is save the video and voila. Remember that you can see what the resulting video will look like by clicking on the combobox that sais 'Input' and changing it to 'Output'. Well there you have it, now you can easily convert your favorite videos to your PSP. Have fun! [UPDATE 23/06/2008] Updated the list of restrictions on the PSP.