Archive for March, 2008

Profiles and FFmpeg

Wednesday, March 26th, 2008

I think I ought to tell about the idea that fellow FFmpeg participant Robert Swain (I still wait for him to complete AMR-NB decoder) tries to champion. I mean encoding profiles.

The idea is quite simple – allow users use convenient presets instead of command line black magic, so simple commands like

ffmpeg -i input.vob -preset dvdrip -preset hq_mp3 output.avi
ffmpeg -i input.avi -preset flash_youtube output.flv
ffmpeg -i input.vob -preset ipod_vid output.mp4

can be used without bothering about bitrate/flags/gop size/whatever.

I also think this will be useful. It will be easier to change options meaning without making additional complications (we still get questions from users that do not know recent ffmpeg expects bitrate to be specified in bits, not in kilobits as before). Just don’t make frontend for it named ffclippy, okay?

Protected: Roads

Wednesday, March 26th, 2008

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A new iron at work

Tuesday, March 25th, 2008

Tech support effect has worked – after I showed my new toy to familiar computer repairman it began to work. RAM installation is a black magic indeed.

So now I have a working x86-compatible box with 1GHz CPU and more RAM and harddrive space than on other boxes combined. I’ve already installed Ubuntu (just the first distro I reached, no actual preferences) and debug environment is almost ready, so I may continue RV[34] development soon.

Here is a photo of it with a piece of paper where its name is written. Try to guess it (and no, it is not related to anime).

My new box

A New Box

Saturday, March 22nd, 2008

I’ve finally got an x86 box. Thanks to immeasurable efforts of Henning Norén who sent it to me.

On this poor quality photo you can see it. This box contains Pico-ITX based computer with more memory than on my other boxes together.

My New Box

The only bad moment is that though I’ve assembled it (and I believe assembled it properly) I can’t make it start up. DC converter (a small board to the right) produces voltages all right, so it’s not a power failure. Hopefully I will resolve this issue in a week, install Linux and resume my work on codecs development.

RV30/40 – status

Tuesday, March 4th, 2008

Just for curious people who really want to know what’s happening in rv30/40 decoder for libavcodec implementation.

I have implemented all main parts of decoder including loop filters, but some of the finer details are missing like parameters that should be passed to loop filters or motion vector prediction. This results into jerky picture in case of B-frames present (and they are often present) and dirty tails after moving objects. See for yourself.

Screenshot of decoder performance

Some example of my rv40 decoder work

Currently the work on this decoder is stalled. In order to fix bugs I have to verify decoded data against reference decoder and that’s not easy. It takes a whole night to get the needed debug data for 70 frames from 320×240 video on my ThinkPad 390. And it takes a lot of space too considering I have about a hundred megabytes of free disk space there.

I want to obtain a small (I don’t have enough space to fit standard desktop), low-power (less than 20-30 Wt power consumption, power blackouts are quite common here) x86-based computer. I know they exist in many variations, but it’s next to impossible to buy one here.

Well, I will finish both encoders. Eventually. Especially if I have enough content to test it with – most files I’ve met (including samples.mplayerhq.hu) are either Japanese TV recordings (anime often bears Chinese subtitles) or Simpsons with crappy translation into Russian (for example, “you rock” was translated as it if was “you are a rock”). Oh, there are also some movie trailers but I fear the need to watch them won’t motivate even Mike.

If you are curious why I chose that shot. I believe it features the character main MPlayer server is named after.