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Conversion Passthrough Settings

conversion passthrough apple tv

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#1 Frood

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Posted 15 October 2014 - 08:11 AM

Hi,

 

We use the Air Video HD iOS app to connect to the AVHD Server to mainly just convert video on our media server which then gets added into iTunes so we can watch the content on Apple TV.

 

Recently (possibly since the new update) I've noticed MKV files taking upwards of 30 mins to convert, rather than less than a minute to convert previously.

 

I have noticed another post about the passthrough settings and I think I've changed them all in the app by:

 

1. In the app, selecting a Video file

2. Tap the (i) under the file title

3. Tap Conversion quality and set all to Preserve Original Tracks: Wherever Possible

4. Tap Passthrough Settings

5. Change/Ensure that: H.264 Video is Optimistic, MPEG Audio is Keep Original, MPEG-4 Audio is Optimistic

6. Direct Streaming (.mp4) is Enabled.

 

Back on the File Information screen, I tap the blue (i) next to "Audio track will be converted" and it shows that it will be "Keeping the original video track" and "Converting Audio track".

 

Yet when I go back to the file list and press and hold on the file and tap "Convert Only" it still takes 30 mins to convert.

 

I've tested by using WinFF with an MP4 Passthrough preset and it converts (remuxes) the video file in less than a minute, so at this stage I'm convinced that it must just be a matter of having some incorrect settings in AVHD after the recent AVHD update.

 

Any tips?

 

Thanks.



#2 admin

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Posted 15 October 2014 - 10:20 AM

Is there any reason listed for "Keeping Audio Track"? What format is audio track in?

 

Also, 30 minute conversion for just audio is way too long. What kind of CPU do you have?



#3 Frood

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Posted 15 October 2014 - 10:34 AM

No real reason, just trying to rule settings out to force passthrough. Audio is in 5.1 AC3.

 

CPU is G2020T in a HP Gen8 Microserver.



#4 admin

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Posted 15 October 2014 - 10:45 AM

The reason should be that "Audio track is not supported by the device". AC3 can not be kept, it needs to be transcoded. The device can not decode AC3. GPU is irrelevant for audio transcoding. Name of the server doesn't help me much, but if it transcodes just the audio 30 minutes it means that either something else is causing CPU load or the CPU is not very powerful. 



#5 Frood

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Posted 15 October 2014 - 10:56 AM

I'll rephrase.

 

CPU is an Intel G2020T 2.5 GHz

 

I have altered the aforementioned MPEG Audio settings under Passthrough to be "Always Convert" and have retested.

 

From what I can tell, Air Video HD is still attempting to uneccesarily transcode the video stream too.

 

As mentioned, I have cross-tested with ffmpeg in passthrough mode and it remuxes the same files in under a minute, just like Air Video HD used to.

 

What I guess I might be after, is confirmation of the exact settings I need to set and where I need to set them in order to force passthrough of the video stream.



#6 admin

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Posted 15 October 2014 - 11:05 AM

If it says "Keeping original video track" then the video track should not be converted. It means video passthrough is on. You can also check that the estimated size closely matches the original size (the difference being audio track).

 

You can start the conversion and send me the logs (Create Archive from Logs) to support (at) inmethod.com. From the logs it is apparent if video is converted or kept.

 

Also you test remuxing with ffmpeg, but in Air Video HD the audio is not remuxed, it is converted because the device doesn't support it. Remuxing it with ffmpeg keeps the original audio (but it will be unplayable on iPhone/iPad).



#7 Frood

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Posted 16 October 2014 - 07:19 AM

Hi,

 

I have attached the zip file with the logs (unique information sanitised) to this post.

 

Attached File  AirVideoServerHDLogs-2014-10-16-07-02-37.zip   2.93KB   21 downloads

 

These logs are of two conversions of different files, but same media type and settings, the first conversion only converted the audio and kept the video, taking less than 2 minutes, the second conversion converted both video and audio tracks.

 

Also you test remuxing with ffmpeg, but in Air Video HD the audio is not remuxed, it is converted because the device doesn't support it. Remuxing it with ffmpeg keeps the original audio (but it will be unplayable on iPhone/iPad).

 

Yes, i should have clarified further. As you say, the audio track from ffmpeg in full passthrough mode will be incompatible with Apple devices. For both of the same files testing in Air Video HD above, my ffmpeg comparison test remuxed the video track and transcoded the audio track into AAC and, after testing, the media plays fine on Apple devices.



#8 admin

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Posted 16 October 2014 - 08:40 AM

Hi,

 

can you please send me screenshot of Download screen of the file where video gets transcoded (tap ( i ) to expand the stream status row) to support (at) inmethod.com ?

 

If it says that it keeps video but still transcodes it then it is a bug of course.



#9 Frood

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Posted 16 October 2014 - 09:01 AM

I have attached a zip file with five screenshots (images cropped due to forum attachment limit).

 

Attached File  Screenshots.zip   476.8KB   26 downloads

 

The first screenshot shows the two files in the conversion queue (one can be seen converting both tracks, while the other can be seen only converting the audio track).

 

The other screenshots are from each of the files' information pages, showing for both files that the video track is to be kept, but the audio track is to be converted.

 

Hopefully I have attached suitable screenshots, if not, please let me know which other screenshots and/or information is required.

 

Thanks.



#10 admin

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Posted 16 October 2014 - 10:59 AM

Hi,

 

I meant the screenshots from "Download" page (which has the quality slider). There is a cell there that says whether the video track will be converted for downlaod (or not) and if you tap ( i ) on the cell, it should tell you why.



#11 Frood

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Posted 16 October 2014 - 01:10 PM

Sorry, it won't let me attach any more files, however, upon viewing the download settings for the file which has been converting both video and audio tracks:

- The Maximum Download Quality slider is set to 720p Estimated Size Less Than 615MB

- Converting Video Track: Track is not within bitrate or size limits

- - (even though the quality slider is set to 720p for a 720p video)

- Converting Audio Track: Codec is unsupported by the device

- - (as expected)

 

It seems that though the Maximum Download Quality slider is set within a file, this is then actually a global setting for the app, which seems a little confusing to me - I was looking for a setting like this in the Settings screen at the start of the app - but at least I have found it now.

 

I have noticed when increasing the Maximum Download Quality slider even by one notch to 720p HQ, the status changes to "Keeping Original Video Track" and "Converting Audio Track", and retrying the conversion takes less than 2 minutes, as expected, which at least gives me a workaround - thank you for that!

 

It seems that the resulting Estimated Sizes from the Maximum Download Quality slider up to and including the 720p setting are arbitrary file sizes - is this correct?

 

If so, then is then the fundamental difference between "720p" and "720p HQ" simply just file size?

 

If not, then what I'm then not sure about, is why, with the slider set to 720p for a 720p video, did it not pass the video track through?

 

Thanks for your patient assistance through this.



#12 admin

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Posted 16 October 2014 - 04:45 PM

Hi,

 

the setting indeed is global. Everything conversion/bitrate/passthrough related is global (except "Force Conversion", which is per file).

 

In your case the video is converted when 720p is selected, because the file to which Air Video Server would convert 720p video is smaller than the original file. With 720p HQ the converted file size would be bit larger (better quality) and also the file size check is much more relaxed. So almost all 720p video tracks (regardless of bitrate) should be preserved. Alternatively you can force Air Video HD to always preserve the track when you tap on the info cell.







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