Question about encoding

[GadgetAddict]

Hi All,

Hope this isn't posted in the wrong place.  I have been downloading a lot of BD rips of various animes, and have been noticing something.  These videos are being encoded with a very high number of reference frames.  Obviously a higher number of reference frames can be good for image quality, but it presents a few problems.  1.  It puts a higher strain on playback devices and 2.  It prevents the conversion of these (typically) MKVs to physical media without completely re-encoding the video.

For example, I downloaded a 16GB torrent of High School of the Dead, bluray rip.  It had 16 reference frames encoded.  The max for 1080p is 4.  h264 is a lossy format, so re-encoding, even at the same bitrate is going to degrade quality, not to mention, re-encoding takes me pretty much a whole day at 2-pass very high quality settings on my i7 @ 4.0 ghz...

Does anyone on this forum do encoding?  If so, why with the reference frames?  Also, noticed the large amount of files utilizing FLAC format, which is uncommon in other ripping/encoding groups...

Finally, this isn't a complaint, so please don't attack me with the "shut up and take it how it is".  Just wondering.

[Lupin]

Hi All,

Hope this isn't posted in the wrong place.  I have been downloading a lot of BD rips of various animes, and have been noticing something.  These videos are being encoded with a very high number of reference frames.  Obviously a higher number of reference frames can be good for image quality, but it presents a few problems.  1.  It puts a higher strain on playback devices and 2.  It prevents the conversion of these (typically) MKVs to physical media without completely re-encoding the video.

For example, I downloaded a 16GB torrent of High School of the Dead, bluray rip.  It had 16 reference frames encoded.  The max for 1080p is 4.  h264 is a lossy format, so re-encoding, even at the same bitrate is going to degrade quality, not to mention, re-encoding takes me pretty much a whole day at 2-pass very high quality settings on my i7 @ 4.0 ghz...

Does anyone on this forum do encoding?  If so, why with the reference frames?  Also, noticed the large amount of files utilizing FLAC format, which is uncommon in other ripping/encoding groups...

Finally, this isn't a complaint, so please don't attack me with the "shut up and take it how it is".  Just wondering.

Most anime encoders don't give a damn about hardware playback.

Non-anime ripping/encoding groups (particularly the Scene) have strict rules (quite ancient rules IMO) that requires hardware compatibility.

[kureshii]

The max ref frames supported in the h264 spec is 16. But most hardware playback devices only support up to Level 4.x, which allows 4 ref frames for 1080p and 9 for 720p.

A higher number of ref frames does not increase image quality, but may aid compression. You’ll have to appeal to the fansubbing/encoding groups to get them to lower ref frames if you want something done about that.

The FLAC audio tracks are typically encoded from lossless audio sources (DTS-HD MA or PCM). Those looking for a release they can watch straight away would likely balk at the filesize, but if you transcode your own MKVs for viewing (some do that for AC3 compatibility with their AV receivers, for instance), FLAC audio is a pretty nice thing to have. Again, rage at the fansub group if you want that changed.

I’m fine with both practices, although I can see why they cause some leechers no end of grief.

[GadgetAddict]

I rip/backup my own blu-rays pretty frequently and I do know from my own experience that animated/non-live action material handles compression very very well.  I definitely think that if they changed their ways from encoding with 16 reference frames to the typical 4 for 1080p, there would be no real drawbacks that would be discernible.  What is the best way to contact these fansubbers/encoders?  I'd like to maybe chat with them if at all possible

[kureshii]

Most groups have IRC channels, listed on their fansub page, which is usually a google search away.

[Lupin]

I rip/backup my own blu-rays pretty frequently and I do know from my own experience that animated/non-live action material handles compression very very well.  I definitely think that if they changed their ways from encoding with 16 reference frames to the typical 4 for 1080p, there would be no real drawbacks that would be discernible.  What is the best way to contact these fansubbers/encoders?  I'd like to maybe chat with them if at all possible

I doubt you can convince them. More reference frames help in the compression especially in animated sources.

[kureshii]

I definitely think that if they changed their ways from encoding with 16 reference frames to the typical 4 for 1080p, there would be no real drawbacks that would be discernible.

There would be no drawbacks apart from increased filesize.

x264 [info]: consecutive B-frames:  1.8%  2.8%  4.4%  23.1%  14.8%  24.8%  12.3%  12.7%  3.3%

Those are stats from a recent 720p encode I made of My Neighbours the Yamadas. It’s a rather low-motion slice-of-life that benefits greatly from increased ref frames. This is encoded at L4.1 so --ref is limited to 9, but you can see that all 9 reference frames are pretty well-used. The number of times 4 or fewer reference frames were used is slightly over 30%.

Most HD encoders have hardware to throw at their encodes, and will happily do so. If you’re looking for L4.1-friendly encodes, seek out groups like OZC and convince them to encode stuff you want to watch

[GadgetAddict]

Interesting.  So basically, you're saying that these encoders typically only view their material either straight from PC or perhaps a HTPC?  I know I'm part of a small minority that likes to burn my stuff to disc, but I'm sure the ref. frame thing would eliminate people with those media players like the WD box...Appreciate the information on their "perspective" on encoding

[GadgetAddict]

Also, the reason I burn my stuff to disc, is because I can easily take my library with me and view things with friends without any fuss.  Also, I like having a nice shelf filled with Blu-Ray cases (I even create the box art)...

[Lupin]

Interesting.  So basically, you're saying that these encoders typically only view their material either straight from PC or perhaps a HTPC?  I know I'm part of a small minority that likes to burn my stuff to disc, but I'm sure the ref. frame thing would eliminate people with those media players like the WD box...Appreciate the information on their "perspective" on encoding

Most hardware players (if not all) cannot play some of the things fansub groups use in their releases (ASS typesetting). To me, playback compatibility limits what groups can do to make better releases. Of course, groups can have hardsubbed typsetting but this is a slowly fading practice.

[kureshii]

http://wdtv.wetpaint.com/page/H.264+reference+frames+specs One of a few compiled wikis for the WD hardware players. The ref frame limitations aren't strictly 4@1080p and 9@720p, but of course it is nowhere near 16 ref frames at all resolutions either.

Many people I know watching their stuff on WDTV and similar set-top boxes either go for L4.1-compatible encodes or 720p releases. The bloated, WDTV-unfriendly encodes are usually downloaded by those with higher-end (HT)PCs.

[Stsin]

I asked about this long ago.  It not only helps with standalones, but those with underpowered CPUs that want to view 1080p using DXVA.  Most scene groups do this, since they are trying to make it the most compatible for all, not those with a specific setup.  Also partially explains why there are so many versions with anime fansubs, unlike the scene.  Going to be even more splits with 10bit depth. While high Ref Frames do help in compressing animation, it's ironic that the trend has been increasingly bloated filesizes at such high ref frames...from TV sources!   btw, I also think FLAC is a waste.  Some groups even convert the AC3/DTS source to FLAC.

I used to purposely look for groups that didn't go above the bluray format, even though my system could play anything.  Just to support the ideal of it.  But technology improves and the latest GPUs can now do 5.1.  And with HTPCs becoming more common as we retire our recent systems (old systems before couldn't do 1080p well without DXVA).  I say bring it on.  Ordered Chapters, 10bit depth, highly animated softsubs....but still think FLAC is a waste of space.

[GadgetAddict]

Oh man, I got real annoyed the first time I inadvertently downloaded something with Ordered Chapters, I had no way (that I know of) to recompile them onto a Blu-ray disc.  Top it off, that first one had 16 ref frames

Anyhow, when I encode BD-9s, I ALWAYS go for AC3 @ 640kbps, utilizing the MA tracks of course.  When I'm working with a BD-25, based on the filesize of the video stream, I might either stick with AC3, go to DTS @ 1.5mbps, or if the video stream is very small, keep the lossless audio.

PS:  I don't convert to BD standards because my hardware doesn't support the higher stuff, I just like burning everything to disc...for posterity

[GadgetAddict]

Some groups even convert the AC3/DTS source to FLAC.

Why on earth would they convert a source like AC3/DTS to FLAC?  I can't see ANY benefit in that.  The loss has already been incurred once they encoded in AC3/DTS to begin with; it's not as if FLAC would recover the lost data...

[kitamesume]

they make it so that it would seem that the copy they've made would look "high quality" if not the best. and please refrain from double posting, you've done it twice on this thread alone.

[Xtras]

Some groups even convert the AC3/DTS source to FLAC.

Why on earth would they convert a source like AC3/DTS to FLAC?  I can't see ANY benefit in that.  The loss has already been incurred once they encoded in AC3/DTS to begin with; it's not as if FLAC would recover the lost data...

I don't know about AC3, but if you take DTS and make it FLAC, often you'll save some space without losing any quality.

They don't encode in AC3/DTS, that is usually just the format that is present on the disc, so while the codec is technically a lossy one, it is the original source.

[GadgetAddict]

they make it so that it would seem that the copy they've made would look "high quality" if not the best. and please refrain from double posting, you've done it twice on this thread alone.

Ah christ.  They were afterthoughts that occurred to me after clicking post.  I suppose I should use the edit button.

As far as what was mentioned about DTS/AC3 being the original source, well, I don't think that that is considered original source, even if that's what's on the disc.  somewhere there is an original, uncompressed/lossless version of the audio for these animes (not released or anything obviously).  They just chose to encode and distribute a version of the movie/episode with AC3/DTS...

EDIT #2 (HAHA!) - In regards to utilizing FLAC on a DTS and saving space, well, that is impressive, and did not know that.  Though, it makes sense, because I feel that DTS is a little bloated to begin with.  To me, AC3 at 640kbps sounds EVERY BIT as good as DTS @ 1.5mbps.  DTS volume levels just seem to be higher is all....  Check out this very interesting study they did regarding audio codecs: http://tech.ebu.ch/docs/tech/tech3324.pdf