Compressed with ffmpeg/x264 but with blocks in the viewer

[caldera]

Hi,

I did compressed a video from .mov ProRes to a highquality 1GB .mp4 using Episode Encoder, and from this 1GB .mp4 to an 20MB .mp4 using ffmpeg (I can't do it directly from the ProRes because I can't read it with ffmpeg).
The quality is great for just that 20MB, but when I stream it from my web, and I see it with a flowplayer viewer, or with the gecko-mediaplayer plugin for firefox in linux, and probably with other viewers, it creates some blocks that aren't in the original compressed video when I played in my computer.
Also this blocks are created diferent in each player.

I attached an image with this blocks.

It is not a problem that has to be with the compression. Three time biggers files create blocks also. And the files I compressed before with the Adobe Media Player did not produced this kind of blocks.

I hope there is some setting in the ffmpeg that could solve this.

What I'm doing to compressed it is this, with 2pass:

ffmpeg -i input.mp4 -an -pass 1 -vcodec libx264 -vpre veryslow_firstpass -b 300k -bt 4000k -threads 4 output.mp4;

ffmpeg -i input.mp4 -acodec libfaac -ab 160k -pass 2 -vcodec libx264 -vpre veryslow -b 300k -bt 4000k -threads 4 output.mp4;

I would thank if someone has any idea what could solve this.
Thank you for your time.

[poisondeathray]

I haven't seen this with the x264cli version . What version of ffmpeg and which x264 build was it compiled with ?

If the 20MB version played locally with a media player looks fine, it would suggest some setting incompatiblity with the flash decoder. Have you tried other OS ? maybe flowplayer in Windows ?

Old versions of flash on Windows had compatibility issue with weightp (similar block artifacts), and you could disable it in the encoder with --weightp 0 . New versions have no issues

[caldera]

I have install ffmpeg version 24460-1 and x264 version 20100722-1 in archlinux.

In Mac is where the blocks are more notable, in linux happens, and in windows doesn't happen, so probably it has to be with the flash decoder.

I'm trying to set --weightp 0, but it says me Unrecognized option '-weightp' , although it uses it in the ffmpeg compression:

"264 - core 104 - H.264/MPEG-4 AVC codec - Copyleft 2003-2010 - http://www.videolan.org/x264.html - options: cabac=1 ref=1 deblock=1:0:0 analyse=0x1:0 me=dia subme=2 psy=1 psy_rd=0.00:0.00 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=4 sliced_threads=0 nr=0 decimate=1 interlaced=0 constrained_intra=0 bframes=8 b_pyramid=2 b_adapt=2 b_bias=0 direct=3 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=60 rc=abr mbtree=1 bitrate=300 ratetol=13.3 qcomp=0.60 qpmin=10 qpmax=51 qpstep=4 ip_ratio=1.41 aq=1:1.00"

I did try it including it as "--weightp 0", "-weightp 0", and "weightp=0", but it doesn't recognize it. I don't know why.

Thank you very much

[poisondeathray]

In Mac is where the blocks are more notable, in linux happens, and in windows doesn't happen, so probably it has to be with the flash decoder.

Yes that observation makes it likely. Did you try and update the flash for mac and linux (up to date ?)

Sorry - I'm not sure what the corresponding syntax ffmpeg syntax for weightp is . I don't use ffmpeg to encode with x264. You might ask at Doom9 or Doom10 forums. (I'm not even sure if it's the culprit for linux or mac flash decoder)

b-pyramid or too many consecutive b-frames might also be the culprit (not on windows, but maybe on mac/linux decoder)

EDIT: something with your settings doesn't match with the preset. For example --preset veryslow shouldn't have 1 reference frame as suggested by your post above (or was that 1st pass information ?)

[caldera]

I've been trying all posibilities to find that finally the weightp is the way to solve this. I did change it to weightp 0, and the blocks disappear in the linux/mac play. Apparenty there isn't a lose in quality.

I tried also with weightp 1, but the results are probably worst than with weightp 2.

I did try also the other options you suggest, b-pyramid and b-frames, but it doesn't have influence in this. Just the weightp.

At the moment I can't update it to the last version, but in Firefox/linux I have the version 10.0 r45 of the flash plugin, so it is very close to the last 10.1 version of flash.

About the x264 presets, it were that of the first pass. The second pass was different, having more reference frames:

264 - core 104 - H.264/MPEG-4 AVC codec - Copyleft 2003-2010 - http://www.videolan.org/x264.html - options: cabac=1 ref=16 deblock=1:0:0 analyse=0x3:0x133 me=umh subme=10 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=24 chroma_me=1 trellis=2 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=4 sliced_threads=0 nr=0 decimate=1 interlaced=0 constrained_intra=0 bframes=8 b_pyramid=2 b_adapt=2 b_bias=0 direct=3 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=60 rc=2pass mbtree=1 bitrate=300 ratetol=13.3 qcomp=0.60 qpmin=10 qpmax=51 qpstep=4 cplxblur=20.0 qblur=0.5 ip_ratio=1.41 aq=1:1.00


I didn't find how to change the weightp preset in ffmpeg. I was looking for information about that, and finally i found this guide: http://sites.google.com/site/linuxencoding/x264-encoding-guide. So I did what is here to use the x264 code directly, having the advantage of have absolute control over the codec.

So I think the problem is solved.

Thank you very much for your help, poisondeathray!

[poisondeathray]

Thanks for reporting back

But the real problem is flash decoder on MAC and LINUX platform. Weightp is part of AVC reference specification , it's just that Adobe hasn't patched /updated their flash decoder for those platforms