Can i get a better conversion quality?

[Toka]

Hi, i am a relative newbie to this. having got gb-pvr working now i wonder if anyone can help...

i have recorded some programs that i now want to watch on my tv, by burning them onto dvd. i have tried to do this as is but my buring software doesn't like it [not sure why], but i also want to be able to put 3 or 4 programs onto a dvd at one go.
as it stands the program size is about 1.5gb, if i use the convert to 1200kbs wmv i get a smaller file but but quality goes. is there any way of telling the conversion to compress at about 3500kbs to improve quality and get a file about half the size of the original.
i tried the divx encoder and the quality was very poor when played back on my lcd tv.
can i do this by changing any of the system files or is there a freeby program that i can use to do this conversion.
i would rather let gb-pvr do it as it happens automatically, but perhaps it wont allow me.

any advice will be appreciated...

[gEd]

gbpvr trancodes using ffmpeg.
You can tweak the command line options by editing them in the config.xml file.
<Conversion name="WMV-1200kb/s" cmd="-y -i {SOURCE_FILE} -vcodec wmv2 -b 1200k {DEST_FILE}" targetExtension=".wmv" />

AutoGK is a good front-end converter that enables you to queue up lots of conversion jobs and supports 2-pass encoding, which is really important for good quality vs size conversions, but takes much longer.

[HtV]

When you open config.xml in notepad (backup first ), look for the following part:

Code:

<CustomFFmpegConversions>
    <Conversion name="XviD" cmd="-y -i {SOURCE_FILE} -f avi -ab 224 -ac 2 -acodec mp3 -deinterlace -vcodec xvid -qscale 5 -vtag XVID {DEST_FILE}" targetExtension=".avi" />
    <Conversion name="DivX" cmd="-y -i {SOURCE_FILE} -f avi -ab 224 -ac 2 -acodec mp3 -vcodec mpeg4 -b 1000k -vtag DIVX {DEST_FILE}" targetExtension=".avi" />
    <Conversion name="Video Ipod" cmd="-y -i {SOURCE_FILE} -title {TITLE_SUBTITLE} -f mp4 -vcodec mpeg4 -s 320x240 -r 15 {DEST_FILE}" targetExtension=".mp4" />
    <Conversion name="Sony PSP" cmd="-y -i {SOURCE_FILE} -title {TITLE_SUBTITLE} -f psp -r 29.97 -s 368x208 -b 768k -ar 24000 -ab 32 {DEST_FILE}" targetExtension=".mp4" />
    <Conversion name="Mobile .3GP" cmd="-y -i {SOURCE_FILE} -acodec aac -vcodec mpeg4 -s qcif -aspect 4:3 {DEST_FILE}" targetExtension=".3gp" />
    <Conversion name="WMV-1200kb/s" cmd="-y -i {SOURCE_FILE} -vcodec wmv2 [B]-b 1200k[/B] {DEST_FILE}" targetExtension=".wmv" />
    <Conversion name="WMV-700kb/s" cmd="-y -i {SOURCE_FILE} -vcodec wmv2 -b 700k {DEST_FILE}" targetExtension=".wmv" />
  </CustomFFmpegConversions>

You could change the -b 1200k in eg 2000k, see if that helps.

[Carlito]

Sorry to resurrect an old thread but i just starting playing with the auto conversion in gbpvr. Since the pvr is now basically the wifes (weird, i seem to remember getting flack for building a pvr, now i hardly get to use it myself ) and she never wants to delete any shows I figure why not convert them to get a smaller file size.
I first chose the default xvid conversion and the quality pretty much sucks. I did some searching and figured I'd change the default -b 1200k to something more like -b 2500k.

Then I came across this post and saw that HTV's config seems to have "-qscale 5" instead of a -b 1200k. Is this a better way to run ffmpeg to convert?
Thanks for any input...

[HtV]

I really don't know, I never use it.:o But I guess I "borrowed" it from some conversion application, so it might be worth giving it a try, that's the only way to find out anyway.

Hans

[zehd]

Sorry to resurrect an old thread but i just starting playing with the auto conversion in gbpvr. Since the pvr is now basically the wifes (weird, i seem to remember getting flack for building a pvr, now i hardly get to use it myself ) and she never wants to delete any shows I figure why not convert them to get a smaller file size.
I first chose the default xvid conversion and the quality pretty much sucks. I did some searching and figured I'd change the default -b 1200k to something more like -b 2500k.

Then I came across this post and saw that HTV's config seems to have "-qscale 5" instead of a -b 1200k. Is this a better way to run ffmpeg to convert?
Thanks for any input...

Just do some tests. qscale works well, but then you shouldn't have bitrate in the command line...

Code:

Like
"C:\Program Files\Devnz\GBPVR\Third Party\FFmpeg\ffmpeg.exe" -y -i "D:\TV\Robot Chicken\Robot.Chicken-S01E11-Toy.Meets.Girl.avi" -vcodec mpeg2video [B]-qscale 5[/B] -acodec mp2 -ab 192k -ar 44100 -ac 2 -vol 1000 -s 640x480 -r 29.97 -aspect 4:3 -async 15 "D:\Temp\Robot.Chicken-S01E11-Toy.Meets.Girl.mpg"
and
"C:\Program Files\Devnz\GBPVR\Third Party\FFmpeg\ffmpeg.exe" -y -i "D:\TV\Robot Chicken\Robot.Chicken-S01E11-Toy.Meets.Girl.avi" -vcodec mpeg2video [B]-b 2400k [/B]-acodec mp2 -ab 192k -ar 44100 -ac 2 -vol 1000 -s 640x480 -r 29.97 -aspect 4:3 -async 15 "D:\Temp\Robot.Chicken-S01E11-Toy.Meets.Girl.mpg"

If I recall

[Deusxmachina]

Then I came across this post and saw that HTV's config seems to have "-qscale 5" instead of a -b 1200k. Is this a better way to run ffmpeg to convert?
Thanks for any input...

In short, yes. A constant bitrate is constant crap unless the bitrate is high, and then the filesize is big. It encodes fast that way, but that's about it. There is also little reason to use 2-pass unless you want a very specific filesize (but it can also hinder quality). CQ (constant quality) is generally the way to go. Experiment a little to figure out how much quality vs. filesize you want, and then pretty much everything will be encoded to that mold.

I don't bother with converting to codecs other than h.264 or xvid. I'll use wmv but only when putting something on my Zune since that's all it takes. Pretty sure my xvid qscale is set to 7. Lower looks a little better but the filesize can be a bit big for me, and higher tends to be a little too low on quality for me. YMMV on what you prefer and for what it's intended for. Obviously, someone could get away with much worse quality for a portable device than for a 50" TV. I'm quite content to watch xvid qscale 7 on a 50" TV.

[Carlito]

I've set it to quality of 5 so I guess I'll see how big the file size is after converting some shows. I'll try out different qualities to figure out which one is best.
Thanks everyone for their input, i'll post back when i figure out what my optimum settings are.