DXV rendering: perenity / auto-constrast?

[mandawah]

Hi there,

I am just wondering: I use Sony Vegas to edit video and then render them to clips for use with Resolume3. Even for 640x480 clips I decided to switch to DXV, since quality seems to be great, and I really see a FPS increase on my system.
Ok, great.

I have 2 questions for the Resolume Team:

1) Would you consider DXV as the ultimate choice for the entire life of Resolume 3? I mean: are you going to continue to develop and use this codec as the primary choice in R3? Do you have enhancement for this codec on the pipeline (e.g. lossless, higher encoding / playback speed, built-in transparency (I'll *really* love this one!!))?

2) When rendering the same clip with DXV or another codec (I did several try with DivX, lossless, other) I noticed that the DXV version is brighter than the others and thus is brighter than my original. Is there some kind of auto-contrast or auto-brightness feature in DXV? If yes, I would appreciate to have the possibility to deactivate it.
Please see attachment: top : "any" codec / bottom: DXV , screenshoted from R3 preview (but I noticed exactly the same difference when playing in other players)

By the way, one last side question: is DXV the only codec that fully use GPU? Or do you also send MJPEG decoding to GPU?

Thanks in advance for your reply.

[edwin]

Hi there,
1) Would you consider DXV as the ultimate choice for the entire life of Resolume 3? I mean: are you going to continue to develop and use this codec as the primary choice in R3? Do you have enhancement for this codec on the pipeline (e.g. lossless, higher encoding / playback speed, built-in transparency (I'll *really* love this one!!))?

DXV will stay the ultimate choice, so far it got great response. We will work on compression speed and other enhancements.
Transparency is almost done, the next update of the DXV codec will support a full Alpha channel.

2) When rendering the same clip with DXV or another codec (I did several try with DivX, lossless, other) I noticed that the DXV version is brighter than the others and thus is brighter than my original. Is there some kind of auto-contrast or auto-brightness feature in DXV? If yes, I would appreciate to have the possibility to deactivate it.
Please see attachment: top : "any" codec / bottom: DXV , screenshoted from R3 preview (but I noticed exactly the same difference when playing in other players)

We will have a look at the Brightness issue, could you send us the original file so we can test and see for ourselves? mail to mail At resolume.com

By the way, one last side question: is DXV the only codec that fully use GPU? Or do you also send MJPEG decoding to GPU?

No, but if we would find a way to do this we certainly will

[mandawah]

Hi Edwin,

thanks a lot for your prompt reply.

the next update of the DXV codec will support a full Alpha channel.

Wow, supergreat! I'll look forward for it!

Regarding the wishlist for DXV, I would say that it would be great if DXV was not so tight with .mov and QuickTime. I am exclusively under MS Windows and I wish I could stick with .avi.
I understand you opted for .mov for some good reasons, but well, I wont' be disappointed to revert to .avi... Also: the only solution one have is to buy QT Pro in order to encode into free DXV, right?

Regarding the DXV Brightness issue, I just sent you the original file by email. Hope this help.

I got another question regarding Codec and migrating from Resolume 2.4, but I think I am going to open a new thread.

Thanks again, and let me congratulate you for your work.

Rgds.

[edwin]

We chose Quicktime because it's cross platform, that saves us the hassle creating a VFW or Directshow codec. Quicktime is just the container, normally Quicktime files don't run that quick in windows but we actually do the real work ourselves there is no performance loss.
You can export to Quicktime from other software like AE and Premiere as well, so no need to buy Quicktime Pro. And then again Quicktime Pro is quite cheap and a handy tool actually.
Also check out this batch converter from Livid Instruments, people on this forum have succesfully used it to convert their material to the DXV format (and it's free).
http://www.lividinstruments.com/software_other.php

We will have a close look at your file.

[bart]

Thank you for sending the file to us. I've done a test too and got the same results. I,ve also rendered the file to h264 and photo jpeg. Those are also a little bit off, Photo JPEG 85% is a bit darker. I'm actually surprised how poor h264 looks, the image has a lot less depth and looses a lot of subtle colours eventhough I set the quality very high, to about 90%. Interesting!

[gradek]

Yeah, I have experienced this issue too. I have noticed some brightness changes when converting from pjpeg to DXV. . Each codec encodes the color information differently. Unless lossless each codec will try to remove "unnessary" information to compress file space. I'm not surprised that the H.264 video looks the worst since it has the highest compression. pjpeg codec I assume only compresses each frame as is, and does not look at temporal redundancy (similarity between frames) like H.264 or any other MPEG.

Here is a little description on video compression theory I found on wikipedia that sums it up good.
http://en.wikipedia.org/wiki/Video_compression

Video data contains spatial and temporal redundancy. Similarities can thus be encoded by merely registering differences within a frame (spatial), and/or between frames (temporal). Spatial encoding is performed by taking advantage of the fact that the human eye is unable to distinguish small differences in color as easily as it can perceive changes in brightness, so that very similar areas of color can be "averaged out" in a similar way to jpeg images (JPEG image compression FAQ, part 1/2). With temporal compression only the changes from one frame to the next are encoded as often a large number of the pixels will be the same on a series of frames.

Bart, what is the DXV codec based on? Is it a modification of another codec?

[mandawah]

Thanks all for investigating.

Interestingly enough, I did not notice a relevant brightness difference when encoding with DivX (with high quality setting). However, as far as I know, DivX does look at temporal redundancies, right?

If DXV looks at temporal redundancies, it does it quite well! Indeed, even with Resolume 2.4, it's the fastest codec I tried when it comes to jump to any frame, play reverse,etc. Also, when start and stop points are not at the very beginning and end of the clip, there is no noticable pause when looping (with DivX there is a long break for instance).

I hope that the brightness things could be fixed without degrading performances. But anyway, it's not a huge problem, results are still much better than with other codecs. I am sure however that the Resolume team won't let DivX have a better color fidelity than DXV

[gradek]

DivX is a type of MPEG4 codec and does take into account temporal redundancies. Thats why it has such small files sizes. it reduced the color information based on frames over time and space. The downside to this is speed. I think pjpeg, mjpeg and dvx do not take temporal information into account. Instead it makes every frame a key-frame with full data, that is not dependent on color information from other frames. That is why you can scrub it back and forth quickly. Each frame is an independent image that can be quickly loaded, even though the file sizes are bigger. H264 and DivX on the other hand take more cpu power to decode, even though the file is smaller. That is why its clunky when you try to scrub it back and forth since the processor is constantly trying to read more then one frame of data at a time. great when playing at normal speed, bad for vjing. The real power behind DXV is that it lets the GPU not the CPU do the decoding. well at leased it does when you use it with R3.

I think your going to get color/brightness shifts no matter what codec you use other then going lossless. Each codec is going to try to compress and simply the information in its own unique way resulting in a shift/change in color/brightness. I don't see a way around it.

[GeeEs]

...You can export to Quicktime from other software like AE and Premiere as well, so no need to buy Quicktime Pro. And then again Quicktime Pro is quite cheap and a handy tool actually.
Also check out this batch converter from Livid Instruments, people on this forum have succesfully used it to convert their material to the DXV format (and it's free).
http://www.lividinstruments.com/software_other.php

Well.. there is no need to buy QT pro if you own AE...However... I don't think a lot of people have that (legal)
I always ask myself this thing about AE and similar software.. lots of people use it.. but it is one of the most expensive tools I know...(especially if you only use it to export...?!?!). Are you crazy! you don't need that software to export!!
I would always buy QT pro in the first place... it's cheap.. $30,00 I guess... and the Livid thing works great too indeed ! AE is nice for a lot of things but heavy overkill for exporting imho

[mandawah]

Hi there,

More input on this "DXV Brightness" subject.
[But before let me just say: you Resolume guys are crazy: I just made a few test with 1080 DXV mov files: I have been able to mix 3 of them (did not test with more) with Luma-key composition, resizing, synced with bmp, etc.: The ouptut at full res was 38fps with 2 screens! I am amazed, this thing rocks!]

Ok: please have a look at the (partial) screenshot below. As you can see Layer 1 is 100% opacity with alpha. I thus expect the output to be identical to the clip itself (it's the DXV version I am playing), but:
- The brightness of the Preview monitor is even lighter than the "output monitor".
- The "output monitor" colors are very close to the DXV clip colors when played outside Resolume.
- On my second screen (fullscreen output), the colors are similar to the one of the "output monitor" window.

So basically it seems that brightness of preview monitor is not exactly right.
Again this is not really annoying, but I thought you might like to know this.

Thanks all for the hints about using livid program to convert to DXV.

Regards.