7 Replies Latest reply on Dec 16, 2008 7:54 AM by (jean_gaudel)

    Export from PP in uncompressed 10 bit darker than export as H264

      First, I want to say that I am still fairly new to video, but coming from 40 years of photography, digital since my first 1Mpx Epson. I have been working lately on very large composite images of up to 100 Megapixels, shot in sections with a Canon EOS40D. I like very detailed images, and had stayed away from video until now because of the lack of quality.
      But HD is here now, and Blue Ray, and I am now shooting video and animation in HD1920X1080 with a JVC-GZ-HD7.
      After starting with the excellent iMovie 08 on my trusted 4 year old G5, I quickly realized it wouldn't cut it anymore, and upgraded a few months ago to the latest MACPRO 2x2.8MHZ Quad core with 10GB of RAM, 4X1GB hard disks, 2 of them in a RAID 0, the other 2 as scratch disks.I am running the latest version of Leopard 10.5.5

      I am recording uncompressed footage directly to disk through HDMI, and editing the footage in full HD 1920X1080p with PP CS4. Even though I can import the uncompressed video in PP, it can't play it, so I convert the clips first to Quicktime AIC. They still look very good.
      As this forum amply proves, the new PP is buggy, but by and large, it works OK for me in HD, except for the bug in AME that resets the bit rate to 1000 when exporting as Quicktime , causing the movies to be very poor quality. But when setting the export Format directly to H264 , the output is excellent, and looks almost identical to what I see in the preview pane in PP CS4.
      My primary purpose for the moment, until I get a Blue Ray burner, is playback from the computer, either on my 30" Apple Cinema Display , or a Panasonic 50" Full 1080p HD Monitor, in the highest possible quality.
      So I have been conducting numerous tests to find the settings for the best possible quality, as well as the settings for an optimum acceptable level of compression (in my book). My tests seem to show that Divx is the way to go. The high quality but very large 1.52 GB mp4 movie exported from PP with the H264 format setting can be reduced to a mere 380MB IN DivX, and looks almost identical. Amazing really.
      But as you guessed, I am a bit of a perfectionist, and wanted to see the best possible quality, period, regardless of size. Exporting from PP as 1920x1080 Quicktime movie with the Codec set to YUV 10 bit 4:2:2, I got what I expected to be the best 81GB movie. The problem is that it was much darker than what I saw in the PP preview pane, and the H264 version of the same. I am well aware that Quicktime tends to lower the gamma and wash out images, and have been shooting darker footage to compensate for that, but I do not know enough to understand why that is. Anyhow, here I am.
      My fix was to lower the gamma of all the clips in the timeline from 10 to 8 ( I tried to select all the clips and apply them the gamma correction at the same time, but it didn't work).
      The preview in PP now looks washed out, but the new 82GB uncompressed 10 bit export looks just fine. Unfortunately, it will no play in Quicktime, even on my fast machine, and really in the end does not look any better on the screen than the 1.52GB PP export with H264, or for that matter, than the 381MB DivX version. I am very pleased with that, but also very puzzled. This is a rate of compression of 1:240! The only problem with the DivX version is that the image of vertical bars moving across the screen fast tends to break up in sections. I will be continuing tests till that doesn't happen anymore.
      Has anybody done this kind of testing? Can anybody corroborate my findings and explain to me how this is possible? Any feed back at all will be welcome, as there is not that much out there stIll about HD1080p.
      Thanks in advance.
      JJ