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Remux without reencoding for MKV, AVCHD, etc. in Push
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wmcbrine

Joined: 04 Jan 2008
Posts: 2010
Location: Maryland

Posted: Fri Jul 08, 2011 6:23 am Post subject:

lucasnz wrote:

Ths is by design.

OK. But I'm not adopting that.
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jcthorne

Joined: 30 Jan 2008
Posts: 243
Location: Houston, TX

Posted: Fri Jul 08, 2011 12:32 pm Post subject:

Iluvatar wrote:

So far works great. DTS audio and >448k AC3 is transcoded.
.

There is no need to transcode 640kbps AC3 tracks for the Premiere. They play fine. It has been reported that they play fine on a Series 3 now as well but did not last year when I upgraded.

jcthorne

Joined: 30 Jan 2008
Posts: 243
Location: Houston, TX

Posted: Fri Jul 08, 2011 12:35 pm Post subject:

lucasnz wrote:

txporter wrote:

wmcbrine wrote:

Note that, by using select_audiocodec(), your patch will transcode otherwise-compatible AAC tracks.

You are saying that H.264 video with AAC audio will transcode with this latest patch? Not good. I transcode everything to AAC so that I don't have to re-encode audio for my idevices.

Ths is by design. I find the tivo gets the channels mixed up with 6 channel aac audio.... So up to now my process has been to manually transcode aac audio to ac3.

2 channel AAC plays fine on a Tivo. 6 channel does not. With a 6 channel AAC audio track, Tivo plays the first 2 channels as a L,R stereo audio pair and ignores the others. No processing to DPL or otherwise so dialog is usually lost and the first two channels in an AAC files are not always FL and FR. The 6 channel AAC should be transcoded to 6 Channel AC3. 2 channel AAC sould be left alone.

Iluvatar

Joined: 29 Feb 2008
Posts: 335

Posted: Fri Jul 08, 2011 1:10 pm Post subject:

jcthorne wrote:

Iluvatar wrote:

So far works great. DTS audio and >448k AC3 is transcoded.
.

There is no need to transcode 640kbps AC3 tracks for the Premiere. They play fine. It has been reported that they play fine on a Series 3 now as well but did not last year when I upgraded.

I get that but this was one of the things missing from my original audio transcoding patch, the usage of user preference. My patch ignored the user preference in the .conf file and hardcoded a bitrate into the code (which could be changed to whatever but wasn't as easy).

And btw my 640kbps files don't always play fine on my Premiere. Occasionally I will get a 'broken pipe' when transferring the file and the Premiere says in the ToDo list that the downloaded file didn't match the expected time length (something to that effect). Transcoding those to 448kbps always fixed it.

txporter

Joined: 11 Dec 2008
Posts: 263
Location: Austin, TX

Posted: Fri Jul 08, 2011 6:33 pm Post subject:

lucasnz wrote:

txporter wrote:

Is there a way to not get that by flag or something? I run my pytivo instances off of a tonidoplug, and I don't think it is really up to transcoding video on the fly.

No just the audio will be transcoded the video is copied as per the -vcodec copy command.

If you have debuging enabled the cmd that it run is output to the log file....

Sorry, mis-typed. I understood that it was audio only. I would prefer to see something like jcthorne listed (leave 2ch AAC as-is and only transcode 6ch AAC).

Iluvatar

Joined: 29 Feb 2008
Posts: 335

Posted: Fri Jul 08, 2011 7:54 pm Post subject:

lucasnz wrote:

txporter wrote:

wmcbrine wrote:

Note that, by using select_audiocodec(), your patch will transcode otherwise-compatible AAC tracks.

You are saying that H.264 video with AAC audio will transcode with this latest patch? Not good. I transcode everything to AAC so that I don't have to re-encode audio for my idevices.

Ths is by design. I find the tivo gets the channels mixed up with 6 channel aac audio.... So up to now my process has been to manually transcode aac audio to ac3.

I have found the same thing. What happens during a normal pull or full transcode? Does pyTivo copy the 6ch aac track or transcode it to 2ch? I don't have any samples any more. If it copies then perhaps 'select_audioch' can be called in the 'tivo_compatible_audio' function to compare audio channel requirements. It seems it would go nicely in the 'if mime == video/mp4 section. This would have the benefit of transcoding the 6ch aac tracks during a pull/full transcode as well. You would need to call the 'tivo_compatible_audio' in the remux code though as well it looks like. Let me know if this is all wrong Laughing

lucasnz

Joined: 13 Sep 2010
Posts: 251

Posted: Fri Jul 08, 2011 9:34 pm Post subject:

Iluvatar wrote:

lucasnz wrote:

txporter wrote:

wmcbrine wrote:

Note that, by using select_audiocodec(), your patch will transcode otherwise-compatible AAC tracks.

You are saying that H.264 video with AAC audio will transcode with this latest patch? Not good. I transcode everything to AAC so that I don't have to re-encode audio for my idevices.

Ths is by design. I find the tivo gets the channels mixed up with 6 channel aac audio.... So up to now my process has been to manually transcode aac audio to ac3.

That could be done... I'll look into it.

wmcbrine

Joined: 04 Jan 2008
Posts: 2010
Location: Maryland

Posted: Fri Jul 08, 2011 10:12 pm Post subject:

jcthorne wrote:

The 6 channel AAC should be transcoded to 6 Channel AC3. 2 channel AAC sould be left alone.

Yes, I'd go with that.
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lucasnz

Joined: 13 Sep 2010
Posts: 251

Posted: Sat Jul 09, 2011 1:40 am Post subject:

wmcbrine wrote:

jcthorne wrote:

The 6 channel AAC should be transcoded to 6 Channel AC3. 2 channel AAC sould be left alone.

Yes, I'd go with that.

Can do, does this rule apply to all media files with aac audio, or just mp4s?

wmcbrine

Joined: 04 Jan 2008
Posts: 2010
Location: Maryland

Posted: Sat Jul 09, 2011 1:52 am Post subject:

I'd say all media files with AAC audio and h.264 video, since these are the ones we can remux to MP4. _________________ My pyTivo fork . My page

lucasnz

Joined: 13 Sep 2010
Posts: 251

Posted: Sat Jul 09, 2011 11:20 am Post subject:

What do you think about this? http://repo.or.cz/w/pyTivo/wmcbrine/lucasnz.git/commitdiff/da899ed635aaf650d0b2d12b05ae79b05a6d3edb It should read the number of audio channels (per track) and if the codec is aac and the number of channels is 2 then it will not reencode. Otherwise it will reencode to ac3.

Iluvatar

Joined: 29 Feb 2008
Posts: 335

Posted: Sat Jul 09, 2011 11:53 am Post subject:

lucasnz wrote:

What do you think about this?
http://repo.or.cz/w/pyTivo/wmcbrine/lucasnz.git/commitdiff/da899ed635aaf650d0b2d12b05ae79b05a6d3edb

It should read the number of audio channels (per track) and if the codec is aac and the number of channels is 2 then it will not reencode. Otherwise it will reencode to ac3.

Will this catch all aac samples that are not considered 'libfaad'? I'm not sure I have seen libfaad in a long time. That decoder was deprecated from FFmpeg more than a year ago. If you are trying to find AAC type then I would think a description of 'aac' or 'mp4a' would be more effective.

Also you are searching for ach!=2, what about mono samples (ie. home video from phones or pocket cams)? Would ach > 2 work as well?

lucasnz

Joined: 13 Sep 2010
Posts: 251

Posted: Sat Jul 09, 2011 10:51 pm Post subject:

Iluvatar wrote:

True, looking at wmcbrines code I'll need to check the mime and the test for aac, mp4a only for mp4s. Or videos with h264 encoding...

Iluvatar wrote:

Also you are searching for ach!=2, what about mono samples (ie. home video from phones or pocket cams)? Would ach > 2 work as well?

Good point

I'll update the code soon.

Luke

lucasnz

Joined: 13 Sep 2010
Posts: 251

Posted: Sun Jul 10, 2011 11:19 am Post subject:

Ok, I've updated my code so that h264 video files with aac audio can be remuxed (without reencoding the audio) if they have 2 or less audio channels on the selected track. Otherwise if they have more than 2 audio channels the audio will be transcoded to ac3. http://repo.or.cz/w/pyTivo/wmcbrine/lucasnz.git/commitdiff/bc751c69ba9a4ce5c0e580aaa3b5d66816ac7105 Luke

Iluvatar

Joined: 29 Feb 2008
Posts: 335

Posted: Sun Jul 10, 2011 5:08 pm Post subject:

lucasnz wrote:

Ok, I've updated my code so that h264 video files with aac audio can be remuxed (without reencoding the audio) if they have 2 or less audio channels on the selected track. Otherwise if they have more than 2 audio channels the audio will be transcoded to ac3.

http://repo.or.cz/w/pyTivo/wmcbrine/lucasnz.git/commitdiff/bc751c69ba9a4ce5c0e580aaa3b5d66816ac7105

Luke

Great.

It may be asking too much but do you feel it would be possible to auto prefer an AC3 track over alternate tracks like DTS (as long as they match the preferred language)?

Many video files that I create or have come across offer both types of audio tracks so as to support different devices. This seems it would save time not having to transcode. No worries if not, this is already better than it was.

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