Archive for December, 2010

Reverse Engineering the MOS 6502 CPU [announcement]

Sunday, December 26th, 2010

3510 transistors in 60 minutes

Update: The video recording is now available.

Comparing BitTorrent Downloads of Interlaced TV Shows

Thursday, December 2nd, 2010

In my previous blog post, I was comparing how internet video providers like Hulu, Netflix, iTunes, Amazon and Zune handle interlaced material by comparing an episode of Futurama. This time, let’s see how rips from the BitTorrent network compare to these.

I managed to acquire nine different files (I own several licenses for this episode, and I downloaded without uploading). Some of these have non-english audio tracks and some have hard subtitles, but let’s concentrate on the quality of the deinterlacing. The following list is already sorted by overall quality, first by interlacing quality, then by resolution, then by data rate:

# Filename Mbit/sec Encoder Cropping Resolution fps Deinterlacing
1 Futurama – 09 – Hell Is Other Robots.avi (184287232 bytes) 1.1 MPEG-4 yes 384×288 25 lots of blending
2 Futurama – S01E09 – Hell Is Other Robots.avi (175728640 bytes) 1.1 MSMPEG4 yes 576×432 24.03 lots of blending
3 Futurama – 1×09 – El infierno está en los demás robots.avi (181534720 bytes) 1.1 MPEG-4 yes 640×480 25 lots of blending
4 Futurama 1.09 – el infierno robot – xvid -español latino.avi (183535616 bytes) 1.1 MPEG-4 yes 640×480 23.98 detelecine, blend
5 Futurama – 1×09 – Hell Is Other Robots.mp4 (83770003 bytes) 0.5 MPEG-4 yes 320×480 29.97 detelecine with 30fps dups
6 Futurama – S01E09 – Hell Is Other Robots.m4v (77853226 bytes) 0.5 H.264 yes 480×368 24.97 detelecine
7 Futurama.S01E09. SWESUB.DVDRip.XviD-Enectrixx.avi (183445504 bytes) 1.1 MPEG-4 no 544×384 25 detelecine
8 S01E09 – Hell Is Other Robots.avi (183490560 bytes) 1.1 MPEG-4 yes 640×480 25 detelecine
9 Futurama – S01E09 – Hell Is Other Robots [dd].avi (183492608 bytes) 1.1 MPEG-4 yes 640×480 25 detelecine

Files #1, #2 and #3 show heavy blending that goes beyond just blending the two interlaced frames per five frames. It is likely these files were encoded form a PAL source that was improperly converted from NTSC.

File #4 is detelecined (24 fps), but whenever the telecine pattern was not consistently PPPII (“Robot Hell” pan, end credits), the algorithm reverted to blending the two fields. It is likely this source was encoded from the NTSC DVD.

Files #6, #7, #8 and #9 all seem to be encoded from the same PAL source that was already deinterlaced properly, i.e. a detelecine was done to recover the 24 fps video, and then it was sped up by ~4% to get a 25 fps video. The detelecine is almost perfect: In the end credits, the algorithm properly reconstructed all frames without ever having to blend, but the “Robot Hell” pan is missing the six frames that that only existed as one field.

File #5 is interesting: It is 30 fps, so it has a duplicate frame after every fifth frame, but other than that, it was converted by the same high-quality detelecine as #6 through #9. Since I suspect that the #6-#9 detelecine was done professionally for the PAL DVD, it is weird to see the practically the same result (6 missing frames in “Robot Hell”, but perfect end credits etc.) with the NTSC frame rate here. It almost looks like someone took a PAL DVD (or one of the files #6-#9) and duplicated frames to get an NTSC-compatible signal.

Bittorent Summary

A rule of thumb is that an encoding found on BitTorrent is as good as its source. For those that had a blended source (#1-#3), nothing could fix it. For those that had an excellent progressive source (#6-#9), there was little to be done wrong. The one that had the original interlaced US master as a source did an okay job of deinterlacing.

Also: The PAL DVDs seem to be very high quality.

Comparison to properly licensed sources

Now how do these scene rips compare to legit internet video providers? Well, as my previous article stated, the files on Hulu, Netflix and iTunes have the deinterlacing done wrong, leading to visible and unnecessary degradations of the vertical resolution in some (Netflix, iTunes) or all (Hulu) of the video – but this is arguably still better than the blending of BitTorrent files #1-3. Amazon Video on Demand did an okay detelecine job, although inferior to BitTorrent file #4: On complicated scenes, Amazon halved the resolution, while file #4 did blending. The Microsoft Zune store did a perfect detelecine, which is even better than the one in BitTorrent files #4-9, since it did not miss the 6 frames in the “Robot Hell” pan, but otherwise performs as well as the PAL DVD.

So here are the final rankings of the different sources/files/enodings for the episode “Hell Is Other Robots” of Futurama:

0. NTSC DVD: original broadcast master, 720×480, interlaced, but with the full potential to be perfectly deinterlaced! ;-)

1. Microsoft Zune: perfect detelecine
2. PAL DVD: almost perfect detelecine
3. BitTorrent files #6-#9: almost perfect detelecine, like PAL DVD
4. BitTorrent file #4: okay detelecine
5. Amazon Video on Demand: okay detelecine, judder
6. iTunes, Netflix: buggy deinterlacing, judder
7. BitTorrent files #1-3: horrible blending
8. Hulu: Consistenly halved vertical resolution

So unless you want to do the deinterlacing yourself, the Zune version is the best choice. Which is, unless you actually want to play the video on the devices you care about, in which case you should get the effectively not copy-protected PAL DVDs.