to B frame or not to B frame, that is my question

[deadrats]

sorry, i just couldn't resist.

as the title suggests, for maximum quality, do you guys think b frames should or should not be used? just so you know what it is i'm doing, i have a number of older dvd's that were poorly encoded, with interlacing, some have some noise, most are dark (as in poorly lit), etc.

what i'm doing is using media coder's filters to clean them up and so far have been very pleased with the results (better than i ever hoped to get them).

i convert from mpeg-2/ac3 encapsulated in a vob container to an m2ts container with ac3 audio and h264 video (i basically output a blu-ray compliant file), both input and output are 720x480, the pixel aspect ratio of the input and the output match (either 4:3 or 16:9) and the following filters are used: yadif deinterlacing, deringing, temporal denoiser and auto level set to 'normal' and the output bit rate is set to match the input bit rate (i.e. if the input vob had an average bit rate of 8 mb/s then so does the outputted file).

so, for max quality, should i be going the IPB route or IP route? i understand that b frames allow for better compressibility and thus lower bit rate could be used but i don't believe in bit rate starving my encodes and i have plenty of hard drive space and blu-ray allows for very large file sizes, so the only consideration is quality.

thus, to B or not to B?

[poisondeathray]

sorry, i just couldn't resist.

as the title suggests, for maximum quality, do you guys think b frames should or should not be used? just so you know what it is i'm doing, i have a number of older dvd's that were poorly encoded, with interlacing, some have some noise, most are dark (as in poorly lit), etc.

what i'm doing is using media coder's filters to clean them up and so far have been very pleased with the results (better than i ever hoped to get them).

i convert from mpeg-2/ac3 encapsulated in a vob container to an m2ts container with ac3 audio and h264 video (i basically output a blu-ray compliant file), both input and output are 720x480, the pixel aspect ratio of the input and the output match (either 4:3 or 16:9) and the following filters are used: yadif deinterlacing, deringing, temporal denoiser and auto level set to 'normal' and the output bit rate is set to match the input bit rate (i.e. if the input vob had an average bit rate of 8 mb/s then so does the outputted file).

so, for max quality, should i be going the IPB route or IP route? i understand that b frames allow for better compressibility and thus lower bit rate could be used but i don't believe in bit rate starving my encodes and i have plenty of hard drive space and blu-ray allows for very large file sizes, so the only consideration is quality.

thus, to B or not to B?

If you deinterlace, then it's not blu-ray compatible at SD frame size

If it's a film source, you should IVTC, then encode progressive with 3:2 pulldown and fake interlaced settings

I would use b-frames , if you use a good encoder (e.g. x264) , the b-frame quality is quite high. You can adjust the IP / PB ratios if you want (PB cannot be adjusted if you use mb-tree) . Other encoders tend to have lower quality b-frames, and there can be visible "pulsing" from b to I frame, if you use b-frames and inadquate bitrate. Higher bitrate solves almost everything , except deadzones and shadow detail - most AVC encoders drop detail in these areas

Do some tests with and without and see for yourself.

[deadrats]

If it's a film source, you should IVTC, then encode progressive with 3:2 pulldown and fake interlaced settings

i'm a tad confused, i thought ivtc was only to be used on telecined source and that a true interlaced source could not be ivtc'd, am i not correct?

to the best that i can determine the dvd's i'm cleaning up are true interlaced.

[poisondeathray]

i'm a tad confused, i thought ivtc was only to be used on telecined source and that a true interlaced source could not be ivtc'd, am i not correct?

to the best that i can determine the dvd's i'm cleaning up are true interlaced.

Yes that's correct

If it's true interlaced, then you wouldn't deinterlace it. You would encode as interlaced (because just like DVD-video, SD blu-ray only supports interlaced signal - 60i or 50i; native progressive isn't supported at SD frame size) . So you wouldn't use yadif, and you would have to make sure your filters are interlace compatible (many are not)

[jagabo]

I would smart bob (Yadif, mode=1) interlaced video to keep the motion smoothness. If I really cared about the video I'd use TempGaussMC.

I question your "output frame rate = input frame rate" technique. With all that filtering you are creating a new video -- the bitrate requirement will be different. Single frame rate deinterlacing and noise reduction tend to reduce bitrate requirements. Double frame rate deinterlacing would increase the bitrate requirement. Brightening the picture tends to increase it. I would guess is you're reducing the bitrate requirement if you are using single frame rate deinterlacing, increasing it if you are using double frame rate deinterlacing.

My experience is similar to poisondeathray's: x264's b frames aren't much lower quality than i and p frames (unlike typical Xvid and MPEG 2 encodings where the b frames are more noticeably lower quality). On the other hand, b frames only reduce the bitrate requirement by 10 or 15 percent (ie, if you compare CRF encodings with and without b frames). In the end, I don't think you'll see much difference.