tablet-encode 2.20
 

Hi,

I was using tablet-encode for the first time today on a Mac and wanted to share some things that will hopefully help others save time.

I found that I had to build mencoder from source as I couldn't find an up to date binary. No big deal, default options are fine.

Perl is present by default so I didn't have to install that.

From here I tried to convert a DVD I had ripped to my hard drive. It wasn't obvious to me that I didn't need to tell mencoder to use the -dvd-device option as tablet-encode will detect this case based on the prescence of the VIDEO_TS folder. Nice touch but I missed this in the documentation.

Having figured that out, I then tried a best preset conversion and got a zero length file. There were some cryptic errors on the console but nothing too helpful. I finally tried running the same command line outside of tablet-encode and found that the lavc audio encoder wouldn't handle mp3.

It would be nicer if tablet-encode and mencoder gave the same output as it seems tablet-encode suppresses some useful information. In this case I found that I needed to install lame.

Back to google, compile from source, install lame.

Now tablet-encode finds that mencoder supports mp3lame and tries to use it. This resulted in another silent failure of mencoder for me. But I found that if I instead used lavc and told it to use libmp3lame that it then worked.

if ($options{'copy-audio'} or (($info->{aformat} || '') eq '85') && (($info->{abitrate} || 0) <= $preset->{abitrate})) {
push @params, '-oac', 'copy';
$af = '';

#} elsif (&mencoderSupports('oac')->{'mp3lame'}) {
# push @params, '-oac', 'mp3lame',
# '-lameopts', 'vbr=0:br='.$preset->{abitrate}.
# ($preset->{abitrate} < 64 ? ':mode=3' : '');
} else {
push @params, '-oac', 'lavc', '-lavcopts', 'acodec=libmp3lame:abitrate='.$preset->{abitrate};
}

Finally I had an avi and I tried several of the presets.

But not being satisfied with less than perfect, I tried 2 pass encoding and again found a silent failure. Running from the command line I found that mencoder didn't like a non zero minimum bit rate.

[mpeg4 @ 0x1023800]Warning min_rate > 0 but min_rate != max_rate isn't recommended!
[mpeg4 @ 0x1023800][lavc rc] Error: bitrate too low for this video with these parameters.
Could not open codec.

So I made the minimum rate zero.

':vrc_buf_size=450'.
#':vrc_minrate='.int($ovbitrate / 2).
':vrc_minrate='.int(0).
':vrc_maxrate='.max($ovbitrate * 1.25, 1000);

And now I can do a two pass encode.

I'm not sure why the player would require a minimum bit rate but I suppose it's possible.

Frank

Re: tablet-encode 2.20
 

Frank,

I haven't got a Mac anymore, so this testing is appreciated.

I'll see if I can do something about the error reporting in this case (and maybe even host an OS X binary of mencoder); and also test your patch on other platforms to see if it can be included.

Cheers,

Andrew

Re: tablet-encode 2.20
 

sorry to jump in off-topic, but is there any way
that tablet-encode can grab subtitles?

Re: tablet-encode 2.20
 

I'm sure you guys have reasons to use the mencoder, but you are aware of the wonderful Knots application, aren't you?

Re: tablet-encode 2.20
 

Grab from DVDs, or include separate subtitle files which may be alongside a video?

In the latter case, I believe the following should work (but I've never tested it. See man mencoder for more options):

As for the former, perhaps -m-sid -m... could help?

Re: tablet-encode 2.20
 

Apples and oranges. tablet-encode is designed to take a random video source (DVD, downloaded video, PVR recording) and produce a video you can put on your tablet for watching later.

There are two reasons for doing this, in general:

1. Space: the tablets have limited space and there's no point filling up a couple of gig with a half-hour MPEG2 video recorded on your PVR
2. Performance: the tablets have limited video playback performance, with a number of limitations including format, bitrate, resolution. With transcoding, a higher-resolution video such as a DVD can be shrunk down to a size and format to allow easy playback on your tablet in Media Player, Canola, MediaBox, UKMP etc.

Re: tablet-encode 2.20
 

Not at all ! Knots can also be used to transcode a video on a server and then transfer it on the device to watch it later OR you can watch a video by on-demmand streaming if you have I-NET, so it does both!

Highly suggested app ;)

Re: tablet-encode 2.20
 

Well, tablet-encode came before Knots :-p

Why does there have to be one perfect tool for everyone? With tablet-encode, I can have multiple profiles depending on usage; directly rip a movie (or a series of TV episodes) from a DVD in a single, simple command; transcode an online video or one I have to hand; etc.

Re: tablet-encode 2.20
 

I find that the two pass option fails in 2.20. It just
leaves a size zero output file. 2.18 still works fine.

Re: tablet-encode 2.20
 

Will look at correcting this tonight. Sorry for the inconvenience.