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From: "Daniel W. S. Almeida" <dwlsalmeida@gmail.com>
To: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: "Randy Dunlap" <rdunlap@infradead.org>,
	"r.verdejo@samsung.com" <r.verdejo@samsung.com>,
	"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
	"nicolas@ndufresne.ca" <nicolas@ndufresne.ca>,
	"Mauro Carvalho Chehab" <mchehab@kernel.org>,
	"linux-kernel-mentees@lists.linuxfoundation.org"
	<linux-kernel-mentees@lists.linuxfoundation.org>,
	"Linux Media Mailing List" <linux-media@vger.kernel.org>
Subject: Re: [Linux-kernel-mentees] [PATCH] media: vidtv: fix build on 32bit architectures
Date: Wed, 16 Sep 2020 10:43:42 -0300	[thread overview]
Message-ID: <BAE73C66-D2B7-44A5-8CD9-72D0430BEED7@getmailspring.com> (raw)
In-Reply-To: <CAMuHMdXjA7q-v-mYY9DChC0XQbv9vfW6c3Vfn07-H-FgBr+izA@mail.gmail.com>

Hi Mauro, Geert,

> That doesn't seem to be the right thing to do here.
>
> Assuming that sampling rate is 48 kHz, you'll
> have duration = 1.875, which would be rounded to 1.
>
> In other words, the above is identical to:
>
> au->pts = count
>
> Now, I don't know from where that CLOCK_UNIT_90KHZ came from.
>

Mauro, here's my current understanding:

The values for PTS have to be defined in terms of a 90khz clock. 

So for 30fps video, the values for PTS per frame would be:

frame_num/30 * 90000

so 0, 3000, 6000, 9000...etc

The same math is being used here for audio, but instead we have the
total audio sample count and a 48000 samples/sec


I did miss this rounding error though, I'm sorry.



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      reply	other threads:[~2020-09-16 13:43 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-15 18:05 Daniel W. S. Almeida
2020-09-15 19:25 ` Randy Dunlap
2020-09-16  6:40 ` Mauro Carvalho Chehab
2020-09-16  7:06   ` Geert Uytterhoeven
2020-09-16 13:43     ` Daniel W. S. Almeida [this message]

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