MPEG2 to H.264 Conversion question

[tonyaldr]

I've got a lot of MPEG-2 files that were recorded via TiVo and ReplayTV that are filling up my terabytes of NAS storage and I've finally decided to begin converting them to a more efficient file format while trying not to sacrifice quality. From everything I've read on these forums it seems that H.264 MP4 would be the way to go. The only thing that I'm a bit uncertain of is whether I can reduce the bitrate to get a little better compression. The majority of the MPEG files are 720x480 with a 15000kbps bitrate at 25fps. I get (to my eye) identical quality when I convert using the same settings to MP4, so I was wondering if there is an acceptable bitrate reduction that I can set before I notice pixelation or any other degradation in the quality. I'm using Freemake Video Converter which seems to do a great job. Thanx!

[sanlyn]

I've finally decided to begin converting them to a more efficient file format while trying not to sacrifice quality. . . . . .I'm a bit uncertain of is whether I can reduce the bitrate to get a little better compression.

Reduced bitrate = reduced quality. You can't have it both ways.

[aedipuss]

yes but 720x480 @ 25mbps is excessive in the extreme to start with. mp4 @ 5mbps should look fine. not sure why you would have ntsc standard 720x480 at 25fps though?

[jagabo]

MP4 is a container and can contain video encoded with a number of different codecs. Use an encoder that supports x264 (h.264) and use CRF mode (handbrake?). Pick the quality you want and encode. The lower the CRF you choose the higher the quality. Try values around 15 to 18. Be aware that some of it may need to be encoded interlaced.

[Hoser Rob]

... I'm using Freemake Video Converter which seems to do a great job...

Frankly you could do much better. I tried it on my older machine, it ain't getting near my newer one. Sorry, but that's the way it is.

+1 on handbrake. or vidcoder, which uses handbrake but the interface is a bit simpler. I'm using handbrake mostly myself. It does excellent encoding, it doesn't require non microsoft codec packs, and you don't have to be a total video geek to begin to use it.

You will need to use the high profile to get good quality with either.

Vidcoder does have a target file size mode, which handbrake doesn't support in the new release. I've adapted.

You don't need to worry about that with the constant quality mode that jagabo recommended. But my experience was that if you're not using the advanced options the 2 pass target bit rate or file size gave me better results than cq.

I also feel that a cq of less than 17 is probably overkill in h.264, which uses a log scale. Although since I've learned a bit about the advanced h.264 options I have been using constant quality mode. It's amazing the difference they make in the quality of the output. However the encode will take 3 times longer, which I find unreasonable on my i3 in 2 pass.

But, by tweaking the settings and using cq mode, I can rip a DVD to h.264 in about the same time as a 2 pass 4300 Kb/s target bit rate encode (which is about as good as you're going to get with 720*480 input), but with much better quality and about half the file size.

The advanced settings are a lot more complex and there's only so much you can simplify it. But if you're talking about that much video, it's going to take you a while anyway. Seems to me you may as well learn some of it and get a better archive.

The handbrake docs point you to the mplayer docs x.264 settings, which have good suggestions.

Also look up lord mulder's comments about handbrake settings on the doom9 forum. Real good stuff.

[jman98]

But, by tweaking the settings and using cq mode, I can rip a DVD to h.264

Actually, you CANNOT "rip a DVD to h.264". You seem smart enough to understand that ripping has NOTHING at all to do with CONVERTING to h.264, which is what you are doing AFTER ripping. I would encourage you to say this kind of thing correctly as we already have enough dumb newbies who come on here talking about "ripping to h.264". As lordsmurf pointed out in a great post in the past, you might as well be talking about "going into the kitchen and ripping myself a sandwich" if you're just going to use "rip" to mean anything you feel like having it mean.

[jagabo]

Most of the world outside videohelp.com refers to the entire process of decrypting and converting as "ripping". Give it up.

[AlanHK]

Actually, you CANNOT "rip a DVD to h.264". You seem smart enough to understand that ripping has NOTHING at all to do with CONVERTING to h.264, which is what you are doing AFTER ripping.

The user clicks a button and a DVD is converted to h264.
Or a CD is converted to MP3.

He never sees the intermediate files.
There may not be any intermediate files. It could just all be streamed from disc to decoder to encoder.

So it's a perfectly logical extension of the term to say "rip to $finalformat".
There is no confusion, what else could it mean?

[tonyaldr]

Thanx, guys! I'll see about using Handbrake. One unexpected result was that I did a test of a WMV conversion and an MP4 H.264 conversion of one of the files and the WMV was actually slightly smaller! I kept the fps, bitrate and aspect ratio equal to source. Anyone surprised at that? Again using Freemake.

[jagabo]

Generally:

file size = bitrate * running time (plus a little overhead for the container, subtitles, etc.)

The bitrate in the above equation is the sum of the audio and video bitrates. Encoders often miss the requested bitrate by a few percent. And different encoders have different overhead. So there's no surprise that two different encoders using different containers give slightly different sizes.

[Hoser Rob]

But, by tweaking the settings and using cq mode, I can rip a DVD to h.264

Actually, you CANNOT "rip a DVD to h.264". You seem smart enough to understand that ripping has NOTHING at all to do with CONVERTING to h.264, which is what you are doing AFTER ripping. I would encourage you to say this kind of thing correctly as we already have enough dumb newbies who come on here talking about "ripping to h.264". As lordsmurf pointed out in a great post in the past, you might as well be talking about "going into the kitchen and ripping myself a sandwich" if you're just going to use "rip" to mean anything you feel like having it mean.

Are you kidding? Just how much coffee do you drink? Or are you just naturally anal retentive?

[AlanHK]

Thanx, guys! I'll see about using Handbrake. One unexpected result was that I did a test of a WMV conversion and an MP4 H.264 conversion of one of the files and the WMV was actually slightly smaller! I kept the fps, bitrate and aspect ratio equal to source. Anyone surprised at that? Again using Freemake.

The difference in filesize with the same bitrate may be due to a different bitrate for audio; did you spec that the same too?

Anyway, same bitrate for different codecs doesn't equate to same quality.

It's a matter of opinion, but my rule of thumb is that for the same quality, a DivX needs half the bitrate of MPEG2, and H264 about a quarter.

There are several different versions of WMV, and I never make them, so I can't comment on how that rates.

[tonyaldr]

I hadn't thought about the audio. Excellent point! As to the bitrate point you made - so for my 15000kps MPEG-2 files, I should convert to H.264 with a 4000kps bitrate in order to achieve the same quality? Just want to make sure I've got that right. thanx!

[aedipuss]

you might try vidcoder, a handbrake gui to simplify things a little. remember that mpeg-2 isn't square pixel, so 4:3 should be 640x480 and 16/9 854x480 in h264 1:1 square pixels. also make sure to de-interlace, or in vidcoder use decomb set to default and de-interlace set to off.

[jagabo]

Leave the frame sizes as they are and use PAR flags to get the right display aspect ratio. Encode your interlaced video as interlaced or you'll lose half the temporal resolution.

Interlaced encoding in Handbrake:
https://forum.videohelp.com/threads/344902-Detelecine-decomb-issues?p=2151515&viewfull=1#post2151515

[AlanHK]

I hadn't thought about the audio. Excellent point! As to the bitrate point you made - so for my 15000kps MPEG-2 files, I should convert to H.264 with a 4000kps bitrate in order to achieve the same quality? Just want to make sure I've got that right. thanx!

More or less.
But you should so some tests and compare the results to see for yourself.

Also, any conversion between lossy formats will degrade the quality. The true comparison is when both are sourced from a high quality source, not one from the other.

[jagabo]

I should convert to H.264 with a 4000kps bitrate in order to achieve the same quality?

Standard definition h.264 at 4000 kbps is overkill for most material. Use constant quality encoding (CRF in x264) and you'll always get the quality you specify. The bitrate will vary depending on the material. Some short examples:

source.m2v, 6549 kbps
crf13.mkv, 3831 kbps
crf15.mkv, 2685 kbps
crf18.mkv, 1649 kbps
crf20.mkv, 1229 kbps

Bitrates as reported by MediaInfo (fairly accurate). The x264 encodings were all done with the "slow" preset, varying the CRF setting:

x264.exe --preset=slow --crf=18 --sar=32:27 --output %1.mkv %1

I usually use CRF=18. There are many settings you can change in x264 to give more or less quality. There are special tunings for grain, cartoons, etc. You won't see it in these samples, but x264 has a weakness in dark grainy video -- it will deliver a lot of banding in the dark areas. You can alleviate that with --tune=grain or the --aq-strength setting. Or just use a lower CRF. All those things will increase the bitrate of the final result.

[Cornucopia]

I hear what joe blow is saying about "ripping" but catch this analogy:
It's tax time and people bandy words like "deduction", "exemption" and "donation" around without understanding clearly the implications in the differences - until they get stuck. Then they run to professionals to iron things out but the pro has to make the consumer do some categorizing/organizing so that things that are clearly (to them) exemptions get put in the exemption category, etc. to get the best return for the client.
But you don't hear the client berating a professional for pressing the appropriate use of terms, so it really should't happen here either.
People come here to help get unstuck. First rule of troubleshooting: isolate the problem. To isolate "ripping" software probs, the 1st thing is to isolate what area is not working right. This also requires clarity of terms...

Scott

[jagabo]

People come here to help get unstuck. First rule of troubleshooting: isolate the problem. To isolate "ripping" software probs, the 1st thing is to isolate what area is not working right. This also requires clarity of terms...

When 99+ percent of the world uses the term "ripping" to mean the entire process of decrypting and converting it's pointless to berate posters for that use of the term. Just ask for clarification when necessary.

[tonyaldr]

Thanx everyone!