Support and General Use > Plugins/Viewers
5.5g poor Mpeg Playback
FujiSkunk:
--- Quote from: GodEater on November 06, 2007, 12:58:33 PM ---
--- Quote from: FujiSkunk on November 06, 2007, 11:16:18 AM ---I know that the CPU isn't powerful enough for decode+display, yes. I was asking if it is powerful enough for decode without display. If it isn't, and I now gather it isn't, then I agree resizing won't help.
--- End quote ---
What would be the point of decoding a video only to then not display it ? I'm not sure I see what you want to achieve here ?
--- End quote ---
If the CPU is fast enough to decode a 320x240 video without displaying it, then perhaps decoding, resizing, and displaying at 160x120 would take less CPU than decoding and displaying at 320x240. I don't know for sure that it would, but I'm basing this thought on previous experience.
If the CPU is not fast enough to decode a 320x240 video without displaying it, then obviously this isn't worth pursuing.
GodEater:
Decoding the video isn't the hard bit - resizing it is. That is orders of magnitude more work than decoding or displaying. The iPod is not up to it.
FujiSkunk:
--- Quote from: GodEater on November 07, 2007, 04:06:23 AM ---Decoding the video isn't the hard bit - resizing it is. That is orders of magnitude more work than decoding or displaying. The iPod is not up to it.
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I see. What if it isn't a smooth rescaling, but a simple dropping of pixels?
linuxstb:
It's possible that downscaling the video will give noticable speed improvements (mplayer has a "lowres" option in its mpeg decoder which I think downscales by 50% in the same way as the Rockbox jpeg decoder does).
But personally I don't think it's worth the time and effort to implement it - you will get much better results by re-encoding the video, rather than wasting CPU cycles (and battery) decoding files larger than you're displaying. Remember we are stretching the ipod's main CPU to breaking point by getting it to decode video, so we need to give it all the help we can - not hinder it.
FujiSkunk:
--- Quote from: linuxstb on November 07, 2007, 12:42:56 PM ---But personally I don't think it's worth the time and effort to implement it - you will get much better results by re-encoding the video, rather than wasting CPU cycles (and battery) decoding files larger than you're displaying.
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That makes sense. I was thinking that if this was enough to get smooth playback, then another round of re-encodings wouldn't be necessary, and users could decide which they like better, video that fills the screen or video that doesn't skip.
But battery usage is a good point. If true 160x120 video requires less battery to play than scaled 160x120 video, then I can agree re-encoding should be encouraged.
Thanks again for a great bit of software, guys. If it weren't for Rockbox, I wouldn't have an iPod (and I wouldn't have returned the iPod Classic I originally bought).
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