Videora Converter Settings

[Killerz298]

I have a question about Videora encoding. Should I be using their standard profiles or can I change the profiles for better quality?

Should the output bit rate video and audio match the bitrates from the original file in order to get the best possible result?

Should I use 1 pass or 2?

Which of these gives the best results?
CBR
FQ-VBR
A-VBR
QC-VBR

Also, if my input video is 624*352 (16:9) or 608*336 (16:9) will using the default profile setting it to 720*480 (16:9) be best or will that stretch out the image since it is bigger than the original? I did a test encode with 720x480 and it "seems" correct when viewed on the tivo but is it really or just close? Would a different setting give me better quality? I don't have a widescreen TV.

So for example, say I have an Xvid file with 1029kbps video and 128kbps/48000Hz Audio would I set Videora settings to match that or should I set it to something differently for best quality?

[Dan203]

First off you need to know that TiVo requires the vertical resolution to be 480. So no matter what the video setting has to be ???x480. TiVo best quality is only 480x480, so if the normal TiVo quality is OK with you then that should be fine. However if you want DVD quality use 720x480. I believe Videora will letterbox the picture so the aspect ration stays correct, so you shouldn't have to worry about that.

As for bitrate... You're talking about programs which are encoded in MPEG4 format with MP3 audio. Both of those codecs are considerably more efficent then MPEG2 and MP2, which is what's needed for the TiVo. So you probably don't want to match the settings or you'll end up with worse quality. In fact since you're converting already compressed video your best bet is probably going to be to use as high a bitrate as you can so as to preserve as much as the picture as possible. If these are things you're going to watch quickly and delete, and your TiVo is not tight on space, I'd recommend 5-6Mbps for the video and 256Kbps for the audio.

As for CBR vs VBR... This setting isn't really about quality it's about saving sapce. Two pass VBR will give you better quality with a smaller overall file size. But it'll also take considerably longer to transcode. So it's you're not tight on space I suggest you save yourself some time and go for a high bitrate CBR setting instead.

Dan

[Killerz298]

Thanks for all your help!

Four more questions:

Since the input video is only 624 or 630 etc.... how will making it 720 on output help if it didn't have that resolution to start off with? Would this decrease quality, or just have no effect? Also, what is the max resolution that a NTSC 4:3 tv can display? Isn't anything more overkill?

As to using the max bitrate availible, I think it is 8000 on Videora, but I thought Tivos max bitrate was like 5400 or something? Also if the input video is only like 1035 isn't setting the output to 8000 overkill and just wasting space? Or am I comparing apples to oranges with the bitrates between formats?

Finally, if I do go with VBR, which one of the 3 options is best? Whats the difference between them? What settings should I use?

Also, I am getting like a 5ms audio sync issue when encoding yet when playing the original xvid the audio is fine. When I open the xvid in vdub it tells me that an improper VBR audio encoding was used. Could this be the cause of the problem on reencode?

[Dan203]

Since the input video is only 624 or 630 etc.... how will making it 720 on output help if it didn't have that resolution to start off with? Would this decrease quality, or just have no effect? Also, what is the max resolution that a NTSC 4:3 tv can display? Isn't anything more overkill?

The maximum resolution a NTSC TV can display is 720x480.

As for the resolution of the output file... Adding resolution will never make anything look better. However if you're going to use the original resolution you need to add black bars to the top and bottom to make the vertical resolution 480. Otherwise if you just teel it to make it 624x480 it will stretch the picture to fill the screen, which wont look right.

As to using the max bitrate availible, I think it is 8000 on Videora, but I thought Tivos max bitrate was like 5400 or something? Also if the input video is only like 1035 isn't setting the output to 8000 overkill and just wasting space? Or am I comparing apples to oranges with the bitrates between formats?

A TiVo "Best" recording is about 5400. However it's also only 480x480, so there is less resolution to use those bits on.

As for the bitrates... it's Apples and Oranges. MPEG4 is about twice as efficent as MPEG2, so right there you'll need to double the bitrate to get a comparable picture. Then add in the fact that...

1) The downloaded file is probably VBR encoded, which as mentioned above allows you to use a lower average bitrate at the expense of encoding time, so it has a lower bitrate then an MPEG4 encoded in CBR.

2) It has less pixels then the final TiVo compatible file. (i.e. 624x352 vs 624x480)

3) Is already compressed so you get the copy of a copy syndrom.

And going up to 6Mbps+ is not a bad idea. That being said, just try a couple of tests and see what you can live with. You can use a program like VirtualDub to cut out a small section of the program with dark blacks and perhaps an action sequence and encode it at different rates and find the lowest one that's acceptible to you.

Finally, if I do go with VBR, which one of the 3 options is best? Whats the difference between them? What settings should I use?

For 2 pass encoding A-VBR will produce the best quality.

Also, I am getting like a 5ms audio sync issue when encoding yet when playing the original xvid the audio is fine. When I open the xvid in vdub it tells me that an improper VBR audio encoding was used. Could this be the cause of the problem on reencode?

Probably the audio encoding, but it could also be the multiplexer Videora uses. Audio sync is a very tricky thing to get right.

Dan

[Killerz298]

Awesome, thanks dan! I pulled out the audio and decompressed it and will try doing it this way and see if the sync issue returns.

As for the resolution, am I better off just setting it to 720x480 or would adding the black bars be better? What would be the difference in quality/size if any? Videora has a setting for 704x480, would I be able to just set it to that instead and would videora automatically do the work for me like it did when it was set to 720?

If I go with VBR 2 pass what should I set my min and maxes to? Also, can I get JUST AS GOOD quality as if I used CBR just at the expense of added encoding time? I really don't mind the extra time, I just queue it all up and let it run.

[Dan203]

The resolution thing is going to be tricky. Both the resolutions you mentioned are 16:9. Unfortunately only some TiVos support 16:9 video. The older 140 and 240 series units can handle 16:9 just fine, so simply set Videora to 720x480 16:9 and you'll be fine. However the 540 series units (i.e. the "nightlight" units) don't handle 16:9 letterboxing properly, so they'll only work if you actually have a 16:9 TV. If you have a 540 unit and a 4:3 TV then you'll have to add the black bars or everything is going to look squished.

The whole point of 2 pass VBR encoding is that it uses the first pass to map out the video and the second pass to assign more bits to scenes that need it and less to those that don't. The result is high quality recordings at a lower average bitrate, and thus a smaller file.

Dan

[Killerz298]

The resolution thing is going to be tricky. Both the resolutions you mentioned are 16:9. Unfortunately only some TiVos support 16:9 video. The older 140 and 240 series units can handle 16:9 just fine, so simply set Videora to 720x480 16:9 and you'll be fine. However the 540 series units (i.e. the "nightlight" units) don't handle 16:9 letterboxing properly, so they'll only work if you actually have a 16:9 TV. If you have a 540 unit and a 4:3 TV then you'll have to add the black bars or everything is going to look squished.

The whole point of 2 pass VBR encoding is that it uses the first pass to map out the video and the second pass to assign more bits to scenes that need it and less to those that don't. The result is high quality recordings at a lower average bitrate, and thus a smaller file.

Dan
Yeah I have an older 240 S2 so I am good to go with that. As to VBR what do I set the min and max to?

[Dan203]

For quality I'd go with a minimum of 2000 and a max of 8000.

Dan

[petew]

Videora is built on top of the freeware ffmpeg libraries. Running the command line ffmpeg command I often see errors concerning the DivX file which Videora just ignores. There does seem to be a correlation between the number of errors and loss of Audio sync. Since both ffmpeg and virtual dub are freeware there a good possibility both are making the same incorrect assumptions about the DivX format.

[Killerz298]

Hrm... when using Videora with ANY of the VBR options it encodes for 2 secs and then it is finished. I get a mpg of 0 size with nothing in it. Encoding the SAME file with CBR works fine.

How do I get VBR working?

[Dan203]

Weird. I've never actually used the VBR option in Videora so I hadn't ever run into the problem.

Dan

[Killerz298]

Weird. I've never actually used the VBR option in Videora so I hadn't ever run into the problem.

Dan
Oh well, so I guess it is CBR for me then. Do I need to do 2 passes with CBR?

[gconnery]

p.s. XVid != DivX

[Dan203]

Oh well, so I guess it is CBR for me then. Do I need to do 2 passes with CBR?

No. CBR means Constant Bit Rate. Which means it uses the same number of bits per second regardless of the contents of the program.

Although I thought you posted that switching the audio setting fixed it?

Dan

[Dan203]

p.s. XVid != DivX

They are not exactly the same, but both are subsets of MPEG4 so pretty much anything that can decode one can decode the other.

Dan

[Killerz298]

No. CBR means Constant Bit Rate. Which means it uses the same number of bits per second regardless of the contents of the program.

Although I thought you posted that switching the audio setting fixed it?

Dan
No, I just selected the wrong profile so I thought it worked :p

I tried it with many other video files, same issue. VBR makes the process complete in 2 secs and nothing happens....

Same issue here in 2005

http://www.tivocommunity.com/tivo-vb/showthread.php?p=3455971&&#post3455971

Setting Min and Max to anything besides 0 will cause it to freak out. I don't know if setting it 0 and 0 will actually do anything, but it says it is encoding at 8000+??

Hrm... so I just encoded 2 xvid files at the highest CBR setting of 8192Kbps but when I look at the file properties for the resulting mpg it says:

Sys Bitrate: 440614 kb/s VBR in GSpot (For Both Files)

VirtualDubMod says Avg Bitrate: 5725 Kbps (for one) and 3279 (For the other)

Mpeg Video Wizard says: 4000 kbps (Variable) (For Both Files)

I thought this was supposed to create a CBR file of 8192Kbps? What is happening?