Hi !
I'm starting to create a bunch of "standard" command lines to run FFmpeg, based greatly on Robert Swain's guide to x264... Now I lack some knowledge that I hope to find here...
Most of my encoding goes to mp4 files with H264 codec, but I also need to have a few efficient commands to convert sources to WMV. So I was wondering if anyone had experimented with WMV's and could share a few tricks he/she's understood over time ? Because so far I've run a few tests but most changes I've tried didn't change much, either quality-wise, or file weight-wise. And I have a major something I want to better, and that is the encoding speed. In WMV, encodings typically run at 8 to 10 fps, whereas H264 encodings go as high as 25-30 fps. I don't know if it's an expected particularity of one or the other codec, and that's exactly one of the things I'd like to know.
I'll post here the 2-pass line I currently use, so if anyone sees something irregular or just has a general suggestion to make the encoding better and/or faster, feel free to express yourself !
So thanks in advances to all who will spread their wisdom !
Regards.
Pass 1 :
Pass 2 :Code:-an -pass 1 -vcodec wmv2 -vpre slow_firstpass -passlogfile 123whatever -b 15000k -bt 15000k -r 29.97 From slow_firstpass.ffpreset coder=1 flags=+loop cmp=+chroma partitions=-parti8x8-parti4x4-partp8x8-partb8x8 me_method=dia subq=2 me_range=16 g=250 keyint_min=25 sc_threshold=40 i_qfactor=0.71 b_strategy=2 qcomp=0.6 qmin=10 qmax=51 qdiff=4 bf=3 refs=1 directpred=3 trellis=0 flags2=+bpyramid-mixed_refs+wpred-dct8x8+fastpskip wpredp=2 rc_lookahead=50
Note : I know 15000k as bitrate is rather high, but this is the template for a source file, one for which we must make sure there is no friggin quality loss ! But I tested as well with bitrates as low as 500k and I know rather well what to expect quality-wise.Code:Pass 2 -acodec wmav2 -ab 192k -ar 44100 -ac 2 -pass 2 -vcodec wmv2 -vpre slow -passlogfile 123whatever -b 15000k -bt 15000k -s 1280x720 -aspect 16:9 -r 29.97 From slow.ffpreset coder=1 flags=+loop cmp=+chroma partitions=+parti8x8+parti4x4+partp8x8+partb8x8 me_method=umh subq=8 me_range=16 g=250 keyint_min=25 sc_threshold=40 i_qfactor=0.71 b_strategy=2 qcomp=0.6 qmin=10 qmax=51 qdiff=4 bf=3 refs=5 directpred=3 trellis=1 flags2=+bpyramid+mixed_refs+wpred+dct8x8+fastpskip wpredp=2 rc_lookahead=50
Try StreamFab Downloader and download from Netflix, Amazon, Youtube! Or Try DVDFab and copy Blu-rays! or rip iTunes movies!
+ Reply to Thread
Results 1 to 5 of 5
Thread
-
-
OK, I admit I have used ffmpeg for WMV-encoding very few times,
and only for curiosity // learning purposes, but hey,
from what I read on your post, ffmpeg probably is "wasting time"
on many "unused" options
Yes, unless the ffmpeg implementation of the WMV compression
has been "enriched" a lot, the following switches are pointless:
partitions=-parti8x8-parti4x4-partp8x8-partb8x8
keyint_min=25
qmax=51
flags2=+bpyramid-mixed_refs+wpred-dct8x8+fastpskip
-acodec wmav2 does not support -pass 2
HTH. -
-acodec wmav2 does not support -pass 2
Yes, unless the ffmpeg implementation of the WMV compression has been "enriched" a lot, the following switches are pointless:
partitions=-parti8x8-parti4x4-partp8x8-partb8x8
keyint_min=25
qmax=51
flags2=+bpyramid-mixed_refs+wpred-dct8x8+fastpskip
Great advice, thanks ! -
Apologies for not being clear enough
Do you mean the encoding should altogether crash, or that it just won't matter to the audio that it is pass 2 ?
Besides: you were telling ffmpeg to encode into WMV while using
x264 encoding parameters I suppose ffmpeg, again,
ignores these, and instead it uses the built-in
"default values" for WMV compression. You'd better read and
re-read again the ffmpeg documentation. -
Yeah, I know I didn't do the ideal thing by mixing WMV encoding with x264 parameters... That's exactly why I started this thread, to know what was good or bad to do
I'd be more than happy to read the documentation, if it weren't so vague... I've been looking for the last month for pertinent information but found sooo little... The closet thing I've encountered to an exhaustive guide was Robert Swain's page, and then again, it's limited to x264...
Is there any sign I should watch out for that'd tell me if some parameter is compatible with one or another codec ? Or any other useful advice, for that matter ?
Note on the side : I had to change some of my parameters that, it turns out, didn't fit with my codec. For example, me_method has had to be set to epzs, umh and dia were rejected...
Similar Threads
-
ffmpeg output 2gb limit? Is there one? ffmpeg stops encoding h264 @ 2gb
By BrainiakZ in forum Video ConversionReplies: 14Last Post: 30th Mar 2011, 12:04 -
[FFmpeg] Up encoding speed for wmv's
By Klagar in forum Video ConversionReplies: 5Last Post: 24th Jan 2011, 13:00 -
[Help] wmv to flv with ffmpeg
By Nightslk in forum Video ConversionReplies: 2Last Post: 4th Aug 2009, 12:52 -
Question about FFMPEG WMV conversion
By shaktar in forum Video ConversionReplies: 2Last Post: 6th Feb 2009, 08:46 -
Need a little help here (wmv/mov to flv with ffmpeg)
By yeauxyo in forum Video ConversionReplies: 1Last Post: 9th Jul 2007, 23:08