Lossless compression quirk

[JediNight]

I'm not going to really worry about it, but I'm interested to see if anyone might have an explanation for me:

I transcoded S1 source from 1080p down to 720p via Lanczos4 in AVS, and S2 source is already 720p so I commented out the resize line. Yet the downsized encodes are 12gb while the ones with no resize are 7gb even though both are 720p YV12.

[Kariudo]

Maybe there was more noise in the 1080p source than the 720p source?
That, and resizing introduces some artifacts into the video (depends on which method you use...though I find it highly unlikely that resizing artifacts alone would cause a 5GB gap in filesizes)

[Zarxrax]

Different show compress to different sizes. When you say S1 and S2 I'm guessing you mean two different shows.

[Qyot27]

Different show compress to different sizes. When you say S1 and S2 I'm guessing you mean two different shows.

Or Season 1, Season 2. 1080p could be coming from Blu-ray, while 720p could be an HDTV capture (or worse, an upscale). The differences there could possibly cause it - the 1080p source would retain more sharpness and clarity when downscaled than something captured at 720p or upscaled. The 1080p could also exhibit ringing artifacts from the Lanczos4Resize you used (generally I can't detect it when downscaling, but then again I'm slightly nearsighted).

Also, are you absolutely sure that both are in YV12? If you're using Lagarith for both then I wouldn't doubt it, but if one or both are HuffYUV, be aware that the standard HuffYUV codec doesn't do YV12 - you need ffdshow's VFW encoder to encode YV12 with HuffYUV (and actually, considering this, it might depend on the settings used for HuffYUV-YV12 - using a different prediction mode and turning the adaptive Huffman tables on or off make quite a bit of difference in filesize; aside from the null frames option, I don't think Lagarith has anything comparable to tweak compression efficiency).

[JediNight]

I encoded both in YV12 with Lagarith. And you are right S1 is Season1 from Bluray, while S2 is HDTV (no watermark of course). I couldn't notice any artifacts from the resize, but I'll check more clearly when I get home from Acen. Can't tell quality differences via Remote desktop very well

For future reference, what do you recommend for downsizing then? Just Bicubic?

[Qyot27]

Well, I'm not of the opinion that a change is necessary (I usually use Lanczos4 unless the source is horrible, in which case I drop all the way down to Bilinear), but if you really don't want the extra size then you could try a regular LanczosResize or you could use Bicubic. Or you could still use Lanczos4 but apply some light filtering to smooth out the artifacts after the resize.

[mirkosp]

(I usually use Lanczos4 unless the source is horrible, in which case I drop all the way down to Bilinear)

Honestly, when it comes to anime, I still think that spline36resize is the best resizer. Live action and CG is where lanczos4resize is at.

[Zarxrax]

Sources captured from tv usually look a bit crappy and are lacking in the amount of fine detail present on a nice dvd or bluray. This is why the HDTV captures are so much smaller. Probably.

[JediNight]

I'm not worried about it, was just curious. Submissions have to be in standard DVD spec anyways.