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Re: [mythtv-commits] mythtv branch master updated by cpinkham. v0.26-alpha-16-g2e9333d

 

 

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gnassas at mac

Jul 22, 2012, 10:02 AM

Post #1 of 4 (554 views)
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Re: [mythtv-commits] mythtv branch master updated by cpinkham. v0.26-alpha-16-g2e9333d

On 2012-07-21, at 3:42 AM, Git Repo Owner wrote:

> commit 2e9333db603fede6c73c4501b52f20d8a1610489
> Author: Chris Pinkham <cpinkham [at] mythtv> at Sat, 21 Jul 2012 00:41:47 -0700
> Committer: Chris Pinkham <cpinkham [at] mythtv> at Sat, 21 Jul 2012 00:41:47 -0700
> URL: http://code.mythtv.org/cgit/mythtv/commit/?id=2e9333db603fede6c73c4501b52f20d8a1610489
>
> More HLS encoder fixes.
> - Offset starting timecode to 1 instead of 0 so libavformat sees it as valid.
> - Set extended_data field in audio AVFrame to squelch libavcodec warning.

By this commit things are looking pretty good, maybe earlier commits were equally nice but this is the one I banged around.

The macro blocking in the first few seconds thing is gone and also the progress slider reflects the point in the program. I played something in the FE at 24:30 and also advanced a stream to 24:30 and they were in sync. Great stuff.

AAC audio is terrific when it works but it's really sensitive to hiccups in the source material. I'm on OTA and this is the season for tropospheric interference so that's a problem for me. When there's a problem (a dropout?) in the program the aac encoder writes something that freaks out apple's player control and I get warbling or worse until the player snaps out of it. Sometimes I can fix it by jumping back in the recording like if I let it warble 10 seconds past a dropout and then jump back 5 the audio will play OK. At other times that doesn't work. No obvious rhyme or reason but it's safe to say the aac encoder is high strung.

Streams with mp3 audio work even when there are huge dropouts in the source material so I'm going to use that until I see another aac-related commit. No rush. I'd suggest exposing the aac/mp3 setting for poor soles like me.

You asked about my environment: I watch mostly on a macbook pro with osx 10.7.4 and safari 5.1.7 which are the current versions & I keep up to date as apple releases stuff. I also have first and third gen ipads running IOS 5.1.1 which play fewer streams but still a good number. I wrote my own scripts to slice and dice the stream lists into something I like but the end result is generated html with a video element where the src points to the .m3u8 file on the backend. After I click play all interactions are between apple's player widget and the backend.

- George

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cpinkham at bc2va

Jul 22, 2012, 9:33 PM

Post #2 of 4 (526 views)
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Re: [mythtv-commits] mythtv branch master updated by cpinkham. v0.26-alpha-16-g2e9333d [In reply to]

* On Sun Jul 22, 2012 at 01:02:12PM -0400, George Nassas wrote:
> AAC audio is terrific when it works but it's really sensitive to hiccups
> in the source material. I'm on OTA and this is the season for tropospheric
> interference so that's a problem for me. When there's a problem (a
> dropout?) in the program the aac encoder writes something that freaks
> out apple's player control and I get warbling or worse until the player
> snaps out of it. Sometimes I can fix it by jumping back in the recording

This may be due to timecodes. I don't rebuild them currently, I just
follow what's in the source material and offset it to start at '1'. If
there are dropouts in the source material, it could affect playback. I'll
try to find a recording like this to test with, but if you can provide a
clip, that would help. I was testing a patch the night before last that
will rebuild the timecodes based on the frames encoded, so that should
hopefully fix this issue.

> Streams with mp3 audio work even when there are huge dropouts in the
> source material so I'm going to use that until I see another aac-related
> commit. No rush. I'd suggest exposing the aac/mp3 setting for poor soles
> like me.

I'll look into the possibility of a setting. If the patch I have fixes
the timecode gap issue then I wouldn't need a setting.

> You asked about my environment: I watch mostly on a macbook pro with

Thanks, so you're running fairly new firmware and software. The sound
issues I'm seeing on my iPhone 3GS are probably not the same issue you're
seeing when you have a gap in an input file.

--
Chris
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gnassas at mac

Jul 23, 2012, 4:38 PM

Post #3 of 4 (518 views)
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Re: [mythtv-commits] mythtv branch master updated by cpinkham. v0.26-alpha-16-g2e9333d [In reply to]

On 2012-07-23, at 12:33 AM, Chris Pinkham wrote:

> This may be due to timecodes. I don't rebuild them currently, I just
> follow what's in the source material and offset it to start at '1'. If
> there are dropouts in the source material, it could affect playback. I'll
> try to find a recording like this to test with, but if you can provide a
> clip, that would help. I was testing a patch the night before last that
> will rebuild the timecodes based on the frames encoded, so that should
> hopefully fix this issue.

Here's my most pathological sample - a 3 minute 200 MB clip:

http://files.nassas.com/LotsOfDropouts.mpg

I believe the problem was too much signal for my tuner and after the first few seconds things go downhill until the 30 second mark and then they're in and out for the duration. My FE sends sound over an optical cable to a surround processor and it seems to extract as much audio as is there. Streaming the clip with mp3 audio comes pretty close to what I get with the FE while aac audio is an end to end disaster.

- George

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cpinkham at bc2va

Jul 23, 2012, 10:30 PM

Post #4 of 4 (519 views)
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Re: [mythtv-commits] mythtv branch master updated by cpinkham. v0.26-alpha-16-g2e9333d [In reply to]

* On Mon Jul 23, 2012 at 07:38:44PM -0400, George Nassas wrote:
> Here's my most pathological sample - a 3 minute 200 MB clip:
>
> http://files.nassas.com/LotsOfDropouts.mpg

Thanks, I'll test that with the timecode changes I'm investigating.

--
Chris
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