Support and General Use > Plugins/Viewers
AVI playback
robin0800:
--- Quote ---I guess iPod must have some hardware accelerated mpeg4 decoder but Rockbox programmes don't know how to access it.
--- End quote ---
Yes the ipods have
--- Quote --- Analog Devices ADV7179
--- End quote ---
and some
--- Quote ---Broadcom BCM2722
--- End quote ---
video chips see http://www.rockbox.org/wiki/IpodStatus for details
but the bottom line is that there is no documentation for these chips
sirdan:
Ipod video is slow because it was tested with 320x240 full screen video right? What about 240x176/128 watching in horizontal position?
--- Quote from: dar02 on October 04, 2009, 04:09:53 AM ---But hey, do you want to listen to the music or watching movies on microscopical screen? ; )
--- End quote ---
Heh i dont watch almost at all, probably others do. I just wanted to raise again the discussion. Maybe there is a developer that feel strong on video codecs field ;) Well generally we have many audio codecs, can the audio quality be improved? Thats priority of course but what esle can be done in RB? Mpeg4 playback would be nice addon.
soap:
--- Quote from: dar02 on October 04, 2009, 04:09:53 AM ---Probably (I am not a programmer, I have no idea, maybe I am wrong) iPod also is using dedicated co-processor to decode mp3 and aac music and because of this it is consuming less energy than Rockbox that is using main universal CPU.
--- End quote ---
1 - No. No dedicated mp3 and aac coprocessor.
2 - Rockbox BEATS Apple firmware for MP3 playback.
--- Quote from: dar02 on October 04, 2009, 04:09:53 AM ---You can forget about watching any movie on Rockbox - any of those little processors will never handle any video format in fair FPS.
--- End quote ---
Odd, Rockbox plays back video on the Color/Photo and Nano at fine FPSs.
AlexP:
On everything except the ipod video, Rockbox gets better frame rates than the original firmware (where they do video at all that is).
sirdan:
--- Quote from: AlexP on October 05, 2009, 01:00:57 PM ---On everything except the ipod video, Rockbox gets better frame rates than the original firmware (where they do video at all that is).
--- End quote ---
I think that problem can be resolved for ipod video users.
Since Im keen on video compression/decompression stuff, i decided to do some tests showing how encoding settings influence playback. Im on sansa e200 but it can be applied to others targest as well. Here are my benches on Elephant dream:
240x128; 24fps; 11min realtime playback
240x128; 24fps; 7min bench time
240x128; 15fps; 5min bench time
240x128; 12fps; 4min bench time
176x100; 24fps; 5min bench time
240x128; 24fps; half bitrate; 6:30 min bench
Every file has the same duration, so we see how playback speed scales with different configs. Shorter bench time=battery savings.
Now word about Ipod video. It plays 320x240 24fps clip at 19 fps. So the most simple way to achieve realtime is convert original fps to below 19 fps..;)
Removing frames goes to jerky playback. They will be blended to retain smoothness. Blending will blurry image but not much.
First make avisynth script with dgindexed video source or loaded by dshowsource. Then add at the end of the script
--- Code: ---ConvertFPS(18)
--- End code ---
. AVScript (on windows only) can be used as input for mencoder.exe to produce 18 fps smooth file. All mencoder builds encode mpeg with only 12,15,24,25,30..etc - dvd compatible framerates. It should be patched probably with
--- Code: ---c->strict_std_compliance = FF_COMPLIANCE_INOFFICIAL;
--- End code ---
to remove that limitation. I havent reached that point as i dont know how compile mencoder at now. If anybody is that freaky to make all steps, he should be happy with his videos on ipod video.
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