Mailing List Archive

AudioOutputGraph progress
Hi Mark : Thanks for looking at this (among much else). I have b15f981
running in F32 and have looked at a recorded GTS (Greenwich Time Signal)
on BBC Radio 4. A good AOG could be helpful for editing radio, while
for video the picture provides the most important editing clues.

In radio the positioning isn't accurate or repeatable - and the display
timescale varies too. My recording began 2 minutes early, and the
'imaginary' video frame rate is 25 fps. Hence the start of the final
pip should be at 3000 frames, and the start of the first at 2875.

Stopping playback at the first audible pip shows a frame count around
2810, while the first to show in the AOG has been around 2720 and the
last around 2830. In the past, only step sizes in radio down to 1
second have worked reasonably well.

I tried making improvements in this some time ago, but my efforts seemed
more likely to break things than yield improvements. I hope and expect
that you can do better :-)

Cheers,

John P
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Re: AudioOutputGraph progress [ In reply to ]
On Thu, 11 Feb 2021 at 16:54, John Pilkington <johnpilk222@gmail.com> wrote:
>
> Hi Mark : Thanks for looking at this (among much else). I have b15f981
> running in F32 and have looked at a recorded GTS (Greenwich Time Signal)
> on BBC Radio 4. A good AOG could be helpful for editing radio, while
> for video the picture provides the most important editing clues.
>
> In radio the positioning isn't accurate or repeatable - and the display
> timescale varies too. My recording began 2 minutes early, and the
> 'imaginary' video frame rate is 25 fps. Hence the start of the final
> pip should be at 3000 frames, and the start of the first at 2875.
>
> Stopping playback at the first audible pip shows a frame count around
> 2810, while the first to show in the AOG has been around 2720 and the
> last around 2830. In the past, only step sizes in radio down to 1
> second have worked reasonably well.
>
> I tried making improvements in this some time ago, but my efforts seemed
> more likely to break things than yield improvements. I hope and expect
> that you can do better :-)

Hi John,

The only functional changes I've made to the audiograph code to date
were to fix the crash on macos. The subsequent changes were purely
cosmetic.

In testing those changes, I pretty much decided that the cutlist
editor is a bit of a mess at the moment. Using VAAPI for decoding,
seeking was erratic in a number of ways and as such, if I were using
the editor, I wouldn't be comfortable that the frame displayed is the
correct one (note: software decoding is much better - though I
wouldn't describe it as perfect). Likewise, although I can't be sure,
it really doesn't look like the audio graph is showing consistently
accurate data. I've never really used that functionality and so don't
know whether it is a regression or not. I'm a little more familiar
with the code now.

Going forward, the player code is only part way through a sizeable
re-factoring - and one of the aims is to significantly improve
handling of audio only streams. So I'm hoping that much of the audio
only/radio stream issues will start to resolve themselves. Likewise,
once the current round of changes is done, I'll start looking at the
decoder in a little more detail - which hopefully will start to
resolve some of the minor seek issues.

All told - what I'm trying to say is - stick with it, there is a plan
and I'm hoping it will all come together before 0.32 is released.

Thanks and regards
Mark
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Re: AudioOutputGraph progress [ In reply to ]
On 12/02/2021 09:45, Mark Kendall wrote:
> On Thu, 11 Feb 2021 at 16:54, John Pilkington <johnpilk222@gmail.com> wrote:
>>
>> Hi Mark : Thanks for looking at this (among much else). I have b15f981
>> running in F32 and have looked at a recorded GTS (Greenwich Time Signal)
>> on BBC Radio 4. A good AOG could be helpful for editing radio, while
>> for video the picture provides the most important editing clues.
>>
>> In radio the positioning isn't accurate or repeatable - and the display
>> timescale varies too. My recording began 2 minutes early, and the
>> 'imaginary' video frame rate is 25 fps. Hence the start of the final
>> pip should be at 3000 frames, and the start of the first at 2875.
>>
>> Stopping playback at the first audible pip shows a frame count around
>> 2810, while the first to show in the AOG has been around 2720 and the
>> last around 2830. In the past, only step sizes in radio down to 1
>> second have worked reasonably well.
>>
>> I tried making improvements in this some time ago, but my efforts seemed
>> more likely to break things than yield improvements. I hope and expect
>> that you can do better :-)
>
> Hi John,
>
> The only functional changes I've made to the audiograph code to date
> were to fix the crash on macos. The subsequent changes were purely
> cosmetic.
>
> In testing those changes, I pretty much decided that the cutlist
> editor is a bit of a mess at the moment. Using VAAPI for decoding,
> seeking was erratic in a number of ways and as such, if I were using
> the editor, I wouldn't be comfortable that the frame displayed is the
> correct one (note: software decoding is much better - though I
> wouldn't describe it as perfect). Likewise, although I can't be sure,
> it really doesn't look like the audio graph is showing consistently
> accurate data. I've never really used that functionality and so don't
> know whether it is a regression or not. I'm a little more familiar
> with the code now.

Yes, I'm using software decoding when in edit mode; it's the only option
on this box (el7 3GHz core2duo), and using nvdec on the
similar-but-with-nVidia F32 is more awkward. The main inconvenience now
is still the tendency to pause for 20 seconds when a return to playback
is expected. I suspect is that it was a latent bug in the AOG code. It
didn't happen before October, and keystroke sequences can be adapted to
make it less likely. Thanks anyway...

>
> Going forward, the player code is only part way through a sizeable
> re-factoring - and one of the aims is to significantly improve
> handling of audio only streams. So I'm hoping that much of the audio
> only/radio stream issues will start to resolve themselves. Likewise,
> once the current round of changes is done, I'll start looking at the
> decoder in a little more detail - which hopefully will start to
> resolve some of the minor seek issues.
>
> All told - what I'm trying to say is - stick with it, there is a plan
> and I'm hoping it will all come together before 0.32 is released.
>
> Thanks and regards
> Mark


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