Converting from PAL 1080i25 to 720p50 - proper bitrate / best program?

[alexvsc]

Hello folks,

I've been doing some enconding from 1080i25 to 720p25 via Handbrake, with the following settings:
- Deinterlace: fast
- Bitrate: 3 mbps

Everyhing else on default.

But I'm now looking to encode to 720p50. I understand I should change the Deinterlace to bob, the framerate to 50 of course, and increase the bitrate, but to what values? 5 mbps? 6 mbps?

Also, do you think Handbrake it's still the best option for this?

Thanks!

[LMotlow]

If you deinterlace 1080i 25fps the result will already be 50p.

Bob isn't a smart deinterlace. It simply separates each field and enlarges them into frames with no special interpolation technique for cleaner frames and minimal artifacts. A "smart deinterlacer" is cleaner and sharper.

No, I wouldn't say Handbrake is the best tool for what you're doing. For better results, you'd have to go into Avisynth and take more control over deinterlacers and resizers.

For 720p I'd use 8mbps or higher, but if it's action video or a lot of noise you have more work to do. With the kind of encoders and software used by us poor hobbyists, 3 mbs is way too low anyway.

If you want to keep the h264 or MPEG encoding to spec for official BluRay or authoring, here's the way it's supposed to be done: http://forum.doom9.org/showthread.php?t=154533. If you just want generic 720p, you can do just about anything you want for encoding.

[jagabo]

The "right" bitrate for any particular video will vary depending on the content of the video. So nobody can tell you what bitrate is appropriate for your source. Use quality based encoding instead and you'll always get the quality you specify, bitrate will vary according to content.

[alexvsc]

The "right" bitrate for any particular video will vary depending on the content of the video. So nobody can tell you what bitrate is appropriate for your source. Use quality based encoding instead and you'll always get the quality you specify, bitrate will vary according to content.

I'm mainly capturing sports: soccer, tennis, etc.

[jagabo]

Live sports requires bitrates toward the higher end of the scale. Again, use constant quality encoding and you'll always get the "right" bitrate.

[alexvsc]

Live sports requires bitrates toward the higher end of the scale. Again, use constant quality encoding and you'll always get the "right" bitrate.

But Handbrake does the job right in your opinion?

[_Al_]

Can you set yadif as a bob deinterlacer there in Handbrake? Then it is going to be OK. There is even better bob deinterlacer like QTGMC but for HD it might be overkill, and it is slow and Handbrake does not use it.

Then you set Constant bitrate encoding, CRF, and set it to 18.
If not happy with result set that number lower.
If resulting volume is going to be too large for you set that number higher. And therefore going lower with the quality.

The point is to find your number for that CRF and then you use it all the time. CRF is quality encoding. You set your quality that CRF number represents and then encoder distributes bitrate so it keeps that quallity. Perhaps it is hard to believe if you never heard of it before, but encoder can encode to keep certain quality.

[manono]

But Handbrake does the job right in your opinion?

It might do the job 'right', but it doesn't do the job 'well', as its 'best' deinterlacer is Yadif. I can't discover what it uses to bob, but if it's a basic bob then the results will be bad. Even using Yadif to bob (if that's what it can use), the results won't be optimal.

As LMotlow mentioned, the best bobbers are available in AviSynth. I think I disagree a little bit with _Al_ that a good bobber might be overkill for Hi-Def material. You seem to be concerned with getting a quality result and that's why you're here asking. He's right, though, that the encoding will be slow.

And if by 'right' you're asking if it does quality-based encoding properly, then by all accounts, yes.

[alexvsc]

I will look for AviStynth then, thank you all guys!

[hello_hello]

I'm pretty sure Handbrake's "bob" de-interlacing is Yadif de-interlacing at "full frame rate" (mode 1), ie at 50fps progressive for PAL, as opposed to de-interlacing to 25fps progressive.

Here's my guess regarding Handbrake's de-interlacing options:

Deinterlace fast = Some sort of linear filter that doesn't sound like it'd be very good.
Deinterlace slow = Yadif at half frame rate (skips spatial interlacing check).
Deinterlace slower = Yadif at half frame rate (with spatial interlacing check).
Deinterlace bob = Yadif at full frame rate (with spatial interlacing check) ie Yadif, mode 1.

https://trac.handbrake.fr/wiki/DeinterlacingGuide#deinterlacing
https://trac.handbrake.fr/wiki/DeinterlacingGuide#decomb

Edit: I just noticed there's also a mention of Handbrake using EEDI2 or mcdeint for de-interlacing, along with a whole bunch of options which don't seem to be included in the GUI. I've never tried them. I assume they need to be enabled via a custom command line?
manono could probably offer some advice as to what might be better than Yadif.
https://trac.handbrake.fr/wiki/Decomb#speed
https://trac.handbrake.fr/wiki/Decomb#options

It might also be worth trying the Decomb filter with the output frame rate set to a constant 50fps. I couldn't find a current reference (one including bob de-interlacing), but the way I understand it the bob decomb filter normally outputs 25fps (for PAL) when it doesn't detect combing (interlacing), which I assume means the frame in question is encoded as though it's progressive. It de-interlaces to 50fps progressive (for PAL) when combing is detected (using either blend de-interlacing or Yadif). That'd be when the output frame rate is set to variable. When it's set to a constant 50fps, the non-deinterlaced frames are duplicated to give you a constant 50fps, while the frames where combing is detected are de-interlaced as before.

I haven't done any serious comparing using Handbrake and it's deinterlacing filter vs Decomb, but the advantage of selecting "bob" as the Decomb method would be the frames without combing aren't de-interlaced, and therefore won't be blurred by unnecessary de-interlacing, while the disadvantage is it'd rely on the Decomb filter getting it right, and it may miss some combing (I don't know from experience). I don't know how good the Decomb filter is, but Decomb "bob" rather than de-interlacing "bob" might be worth a try.

Handbrake's log file is somewhat informative. I managed to find an old post (doom9) where I tried Handbrake's bob de-interlacing after it was introduced, to get an idea as to how it works. Here's the relevant bits from the log files (same video each time).

Bob deinterlacing, constant frame rate output:
[12:14:35] sync: got 658 frames, 1316 expected
[12:14:35] render: 1314 frames output, 0 dropped and 0 duped for CFR/PFR

Bob decomb, variable frame rate output:
[12:18:06] decomb: deinterlaced 1070 | blended 88 | unfiltered 78 | total 1236
[12:18:06] render: 1236 frames output, 0 dropped and 0 duped for CFR/PFR

Bob decomb, constant frame rate output:
[12:19:49] decomb: deinterlaced 1070 | blended 88 | unfiltered 78 | total 1236
[12:19:49] render: 1314 frames output, 0 dropped and 78 duped for CFR/PFR

From the log file I'd assume all the frames were de-interlaced with Yadif when the bob de-interlacer was used.
When the bob decomb filter was used, 1070 frames were deinterlaced with Yadif (I assume), 88 frames were blend de-interlaced and 78 were encoded as progressive. The only difference between a variable frame rate output and a constant frame rate output was the 78 "progressive" frames were duplicated.

alexvsc,
Here's links to my old Yadif vs QTGMC comparison encodes, both at 25fps and 50fps. Keep in mind QTGMC is quite slow, especially for HD video.
https://forum.videohelp.com/threads/354092-Converting-video-frame-rates?p=2225116&viewf...=1#post2225116
https://forum.videohelp.com/threads/354092-Converting-video-frame-rates?p=2225237&viewf...=1#post2225237

[hello_hello]

As LMotlow mentioned, the best bobbers are available in AviSynth.

I'd kind of assumed QTGMC was the best quality de-interlacer, followed by Yadif's mode=1? Is there something in between, quality wise, I'm missing out on? Something like MeGUI's option to use TDeint.dll with EEDI2 maybe, or using NNEDI3? I guess there's a lot of de-interlacing methods I've not tried......

[LMotlow]

I see people still use old-timers like mocomp and so forth, some object to motion smear or whatever with QTGMC and whatever. None of them are perfect.

[manono]

I'd kind of assumed QTGMC was the best quality de-interlacer, followed by Yadif's mode=1? Is there something in between, quality wise, I'm missing out on? Something like MeGUI's option to use TDeint.dll with EEDI2 maybe, or using NNEDI3?

Yes, there are quite a few in beteen QTGMC and Yadif, some not even all that slow. I use YadifMod with NNEDI3 to bob on occasion:

EDI=NNEDI3(Field=-2)
YadifMod(Mode=1,EDeint=EDI)

One advantage is that by using NNEDI3 to do the deinterlacing/bobbing, it's using only the current field to generate the new frame and not the nearby fields. This can keep artifacts (noise, crud, scratches, dirt, white or black spots, etc) from spreading around as sometimes happens when using QTGMC. And it doesn't do that 'cleaning' that QTGMC does, which can be either a good or a bad thing, depending.

I'm pretty sure Handbrake's "bob" de-interlacing is Yadif de-interlacing at "full frame rate" (mode 1), ie at 50fps progressive for PAL, as opposed to de-interlacing to 25fps progressive.

When checking yesterday I couldn't find any evidence of it using Yadif for bobbing, and your links didn't show anything either. And since the Handbrake guys brag about how good it is compared to their usual crap deinterlacing, I think they'd mention it if they used it. As for MCDeint and EEDI2, why use Handbrake at all when you can use AviSynth and not have to put up with the Handbrake gibberish which doesn't explain anything very well except to say how good Handbrake is at what it does?

[hello_hello]

I'd kind of assumed QTGMC was the best quality de-interlacer, followed by Yadif's mode=1? Is there something in between, quality wise, I'm missing out on? Something like MeGUI's option to use TDeint.dll with EEDI2 maybe, or using NNEDI3?

Yes, there are quite a few in beteen QTGMC and Yadif, some not even all that slow. I use YadifMod with NNEDI3 to bob on occasion:

EDI=NNEDI3(Field=-2)
YadifMod(Mode=1,EDeint=EDI)

One advantage is that by using NNEDI3 to do the deinterlacing/bobbing, it's using only the current field to generate the new frame and not the nearby fields. This can keep artifacts (noise, crud, scratches, dirt, white or black spots, etc) from spreading around as sometimes happens when using QTGMC. And it doesn't do that 'cleaning' that QTGMC does, which can be either a good or a bad thing, depending.

Thanks for the info. I'll give it a try sometime soon.

I'm pretty sure Handbrake's "bob" de-interlacing is Yadif de-interlacing at "full frame rate" (mode 1), ie at 50fps progressive for PAL, as opposed to de-interlacing to 25fps progressive.

When checking yesterday I couldn't find any evidence of it using Yadif for bobbing, and your links didn't show anything either. And since the Handbrake guys brag about how good it is compared to their usual crap deinterlacing, I think they'd mention it if they used it. As for MCDeint and EEDI2, why use Handbrake at all when you can use AviSynth and not have to put up with the Handbrake gibberish which doesn't explain anything very well except to say how good Handbrake is at what it does?

I can't find any Handbrake info that mentions bob de-interlacing at all. One of the posters in the doom9 thread I linked to was fairly adamant the bob de-interlacing was Yadif, mode 1, so I took his word for it.

From one of the links I posted earlier, on how the Decomb filter de-interlaces. It's old and Bob de-interlacing isn't mentioned.

By default:
When a frame shows a significant amount of combing, decomb runs a tweaked version of HandBrake's "Slower" deinterlacing filter. That's yadif, a spatially (within one frame) and temporally (between several frames) aware deinterlacer. The tweak is that it uses a looks at more pixels when generating the spatial predictions.
When a frame is only very slightly combed, decomb runs a blending deinterlacer called a lowpass-5 filter. This preserves more detail from the image than yadif, and in particular prevents noticeable deinterlacing artifacts on progressive video.
Which deinterlacer is used and whether blending is enabled can be customized via a custom decomb options string, however. See "Mode: Deinterlacing mode" below for more information.

It's probably safe to assume the decomb filter still de-interlaces the same way when de-interlacing to full frame rate, which would mean it'd still use the equivalent of the "slower" de-interlacer when it think it's appropriate, which is Yadif, only it'd have to output 50fps instead of 25fps..... I assume, but that's me assuming and not offering an indisputable fact.

One of the things I don't like about Handbrake is it's not always easy to work out what it's doing, although the log file does offer a fair bit of info ig you're happy to wade through it. If you're just re-encoding progressive video without filtering, then I guess it's hard to go wrong, but yes, if you're going to start playing around with de-interlacing you might as well use Avisynth. If for no other reason than you can preview the de-interlacing before you encode. I don't think Handbrake has a preview as such. It's preview encodes bits of the video and you've got no control over it, and because it encodes to output a preview, it's not really practical for serious previewing. At least that's the way I remember it. I haven't used Handbrake for quite a while.