kozak
3rd October 2007, 22:17
Mpeg2 -> AVC (h.264 Nero Digital) - why I am losing vividness of color?
I'm using Nero Recode to encode some Mpeg2 clips and DVDs to mp4 files using h.264 AVC codec. Nero version 7.10.1.0 (2.5.5.0). All settings maxed out for Nero Digital AVC / Standard AVC profiles (also tried HDTV AVC profile). 2-pass encoding, deblocking -2. About 1000 kbps for video, crop and resize disabled (preserving original resolution).
Overall I get satisfactory results (to my eye) except one:
comparing original mpeg2 video with avc encoded, there is one fairly significant difference: some kind of shift in color, such that mp4 colors are somewhat washed out. What used to be bright vivid red, for example, becomes somewhat darker and not as vivid, and so on. Face color changes somewhat to less natural and so on. I mostly use VLC player to compare, but get the same result with Powerdvd. Note that the end result is still satisfactory, i.e. it is hard to notice this effect unless the resulting AVC file is compared to original side by side. Still, I consider this a fairly significant quality loss subjectively.
I haven't tried some other application yet, but trying to learn Megui and compare. Also, from the past experience, I remember using SimpleDivx for Divx/Xvid encoding and getting about the same effect. But Divx/Xvid never really cut it for me, and I never got serious about using them.
Questions:
1. Is the color distortion that I describe a pretty much universal problem of xvid/divx/avc, a necessary consequence of trying to compress video to a fairly extreme extent? Or is it a problem of Nero Recode, or the settings that I pick?
2. If so, are there perhaps any settings in Nero Recode to alleviate this (at least in theory) - perhaps deblocking value?
3. If so, perhaps other apps like Megui are better than Nero Recode in this particular respect?
4. Unrelated. I remember in the past using dvd -> divx/xvid avi conversion it was necessary to either resize the original video resolution to proper aspect ratio say 4x3 (i.e. 740x480 -> 740x556), or having the encode played incorrectly (i.e. squeezed vertically). It seems this is not necessary anymore. Is there perhaps a byte in mp4 file that sets the proper resize to happen dynamically by VLC when the clip is played? If so, how can I see this parameter? For example I do not see anything useful in GSpot. For a clip 720x480 it shows SAR = DAR = 1.5.
Thanks in advance for any comments.
I'm using Nero Recode to encode some Mpeg2 clips and DVDs to mp4 files using h.264 AVC codec. Nero version 7.10.1.0 (2.5.5.0). All settings maxed out for Nero Digital AVC / Standard AVC profiles (also tried HDTV AVC profile). 2-pass encoding, deblocking -2. About 1000 kbps for video, crop and resize disabled (preserving original resolution).
Overall I get satisfactory results (to my eye) except one:
comparing original mpeg2 video with avc encoded, there is one fairly significant difference: some kind of shift in color, such that mp4 colors are somewhat washed out. What used to be bright vivid red, for example, becomes somewhat darker and not as vivid, and so on. Face color changes somewhat to less natural and so on. I mostly use VLC player to compare, but get the same result with Powerdvd. Note that the end result is still satisfactory, i.e. it is hard to notice this effect unless the resulting AVC file is compared to original side by side. Still, I consider this a fairly significant quality loss subjectively.
I haven't tried some other application yet, but trying to learn Megui and compare. Also, from the past experience, I remember using SimpleDivx for Divx/Xvid encoding and getting about the same effect. But Divx/Xvid never really cut it for me, and I never got serious about using them.
Questions:
1. Is the color distortion that I describe a pretty much universal problem of xvid/divx/avc, a necessary consequence of trying to compress video to a fairly extreme extent? Or is it a problem of Nero Recode, or the settings that I pick?
2. If so, are there perhaps any settings in Nero Recode to alleviate this (at least in theory) - perhaps deblocking value?
3. If so, perhaps other apps like Megui are better than Nero Recode in this particular respect?
4. Unrelated. I remember in the past using dvd -> divx/xvid avi conversion it was necessary to either resize the original video resolution to proper aspect ratio say 4x3 (i.e. 740x480 -> 740x556), or having the encode played incorrectly (i.e. squeezed vertically). It seems this is not necessary anymore. Is there perhaps a byte in mp4 file that sets the proper resize to happen dynamically by VLC when the clip is played? If so, how can I see this parameter? For example I do not see anything useful in GSpot. For a clip 720x480 it shows SAR = DAR = 1.5.
Thanks in advance for any comments.