export lossless from MP4 to MP4

[pierret18811376]

Hello,

My video source is MP4, and I would like to keep MP4 for the export. But my goal is to have lossless quality for the export in MP4.

I don't want to use other format (like ProRes or DNX...). 

Is it a simple way to be lossless in that case (without going into settings) ?

[R Neil Haugen]

Lossless long-GOP ...  um ... now, that's the trick, innit?

Long-GOP formatting/encoding was designed to be as visually lossless as possible, while throwing out a high percentage of file data to create the smaller file size. By intent, it throws out data.

The only way I know to approach full lossless with that format is to set the level and Mbps way, way up, and then you can mostly sort of make it ... but of course, your file size after export is naturally a LOT bigger also. Data takes space, simply put.

Let's see if someone else has another idea.

[Sumeet Kumar Choubey]

Hi pierret18811376,

H.264 and HEVC are not lossless codecs by default. However, if you're experiencing compression artifacts or quality loss after export, you may try increasing Target Bitrate under Bitrate Settings and enabling the options Render at Maximum Depth & Use Maximum Render Quality. Hope it helps.

Thanks,

Sumeet

[ThioJoe]

Like the others mentioned, if it's MP4 (and likely h.264) then it already compressed and therefore is not lossless.

So I'm assuming you mean no loss in visual quality from the original. 

I'll just add to Sumeet's advice, and suggest you ensure the video's target bitrate at least as high as the original source, and probably a good amount higher (say 25%+ higher?) just to be safe (since it's probably a variable bitrate so depending on your edits, certain parts might be allocated more data than the rest).  You can check the bitrate and other details about the video file using a tool like MediaInfo which is pretty popular.  

Also set the h264 "profile" to at least "Main", not Baseline. You can read about the profiles in this explanation on stack overflow. Though if you notice with MediaInfo (or some other tool that shows this info) that the original MP4's profile is "High" instead of "Main", obviously set your output to High as well. Or if you want you can just take the guesswork out of it and always set it to High. Like the linked post describes, the profile only indirectly affects quality by how efficiently it can compress based on a given bitrate.

[pierret18811376]

I give you below the video details of my source video.

In PP, I have found that "hardware encoding" was giving me some problems (compression, glitches), so I have chosen to use "software encoding".

By choosing "software encoding", what settings, do you advise me to enter ?

Format : MPEG-4
Format profile : Base Media
Codec ID : isom (isom/iso2/avc1/mp41)
File size : 76.6 MiB
Duration : 5 min 26 s
Overall bit rate : 1 970 kb/s
Frame rate : 21.414 FPS
Writing application : Lavf58.76.100

Video
ID : 1
Format : AVC
Format/Info : Advanced Video Codec
Format profile : Constrained Baseline@L3.1
Format settings : 1 Ref Frames
Format settings, CABAC : No
Format settings, Reference frames : 1 frame
Format settings, Slice count : 10 slices per frame
Codec ID : avc1
Codec ID/Info : Advanced Video Coding
Duration : 5 min 26 s
Source duration : 5 min 26 s
Bit rate : 1 832 kb/s
Width : 1 190 pixels
Height : 668 pixels
Display aspect ratio : 16:9
Frame rate mode : Variable
Frame rate : 21.414 FPS
Minimum frame rate : 11.141 FPS
Maximum frame rate : 47.628 FPS
Original frame rate : 24.000 FPS
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Progressive
Bits/(Pixel*Frame) : 0.108
Stream size : 71.2 MiB (93%)
Source stream size : 71.2 MiB (93%)
Writing library : x264 core 164 r3095M baee400
Encoding settings : cabac=0 / ref=1 / deblock=1:0:0 / analyse=0x1:0x1 / me=dia / subme=1 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=0 / me_range=16 / chroma_me=1 / trellis=0 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=0 / threads=10 / lookahead_threads=10 / sliced_threads=1 / slices=10 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=0 / weightp=0 / keyint=250 / keyint_min=24 / scenecut=40 / intra_refresh=0 / rc=crf / mbtree=0 / crf=24.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00
Color range : Limited
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709
mdhd_Duration : 326207
Codec configuration box : avcC

[RjL190365]

The problem with what you are wishing for is that it is impossible no matter what. Every single MP4 (H.264 and HEVC) encoder in existence always re-compresses video no matter what. The only feasible solution is in one of the replies: Set the bitrate as high as you comfortably can (this means higher than the bitrate of the source video) in order to minimize quality loss.

[pierret18811376]

When I talk about "lossless", I mean no loss in visual quality from the original.

[R Neil Haugen]

The whole thing with compression patterns like used in the long-GOP H.264 and 265 codecs is figuring out how much is visually lossless, which can very depending on how much motion, how much fine detail, and also how much color data was thrown out to beging with. Add on, how 'big' the display it will be shown on is.

If it was encoded originally as 4:2:2 10 bit, then you can so some color correction and tonal changes and still compress to a medium level long-GOP and still get by with most things. 

But if it was 4:2:0 color data initially, then you have much less color/tonal correction work before visible 'banding' and 'macro-blocking' occur.

If it was the 4:2:2, and you're careful of export settings, you might make 2-3 generations before seeing degradation. With 4:2:0, you might make a couple generations as long as any color/tonal work was very minimal, and you use pretty large settings for file size ... meaning higher Mbps settings. A LOT higher.

But it will vary with subject matter, movement, and quality of original file ... so it's not a 'set' thing. You have to test to find what works for that file.

[pierret18811376]

Hi @R Neil Haugen 

In your precedent message you said :

"The only way I know to approach full lossless with that format is to set the level and Mbps way, way up, and then you can mostly sort of make it ... "

So you are talking about "Levels" and "Mbps".

I have tried to find where is the "level" setting, and I have found this (see blue arrow). Is it correct ?

This level is actually set to 3.1.  Is it too low according to you ?

But I do not found the "Mbps" setting. Where is it ?

And in your last message you are talking about "color data".  I have seen that the color data of my source video is "4.2.0". So if necessary I will have to go in "Lumetri color" in order to better the colors : Is it correct ?

[R Neil Haugen · Accepted solution]

First, yes, that's the levels I was talking about. You'll want at least 5.1.

Above that is the Profile, and again, the lower options in the drop down are higher capabilities.

The 4:2:0 designation is how much color data is kept in the file. You would do well to look online for information.

4:4:4 is full data for brightness and color data. 4:2:2 loses some color data to save file space, but our eyes can't tell the difference for color, as we are far more sensitive to minor brightness issues. 

4:2:0 drops more color to save more file space, and is low enough on color data you cannot do much tonal, color, or saturation changes without creating obvious banding on smooth surfaces or macro-blocking.

And once the color data has been tossed, as in going to 4:2:0, you can't get it back. So your original files are pretty low on color data to begin with.

[pierret18811376]

Hi @R Neil Haugen 

When you talk about "Mbps", are you talking about bitrate ?

[R Neil Haugen]

Yes.