From: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
To: ffmpeg-devel@ffmpeg.org
Subject: Re: [FFmpeg-devel] [RFC PATCH 1/3] aacdec: always skip the first 2048 samples if there's no side data
Date: Tue, 12 Sep 2023 09:10:57 +0200
Message-ID: <AS8P250MB074484A0312A8401DBB6EF3D8FF1A@AS8P250MB0744.EURP250.PROD.OUTLOOK.COM> (raw)
In-Reply-To: <Ne7-l4q--3-9@lynne.ee>
Lynne:
> For some reason, this was never set, which meant all **raw** AAC in ADTS
> streams, except faac, had extra samples at the start.
>
> Despite this being a standard MDCT-based codec with a frame size of 1024,
> hence a delay of 1024 samples at the start, all major encoders, excluding
> faac and FFmpeg, use 2048 samples of padding.
>
> The FFmpeg encoder will be modified to also output 2048 samples of padding
> at the start, to make it in line with other encoders.
Does this also have actual advantages besides "being in line with other
encoders"?
>
> Yes, this leaves FATE pretty sad. Will fix it with the real version of the patch.
>
Didn't we once guess the number of skip samples like this, only for this
guesswork to be removed intentionally? (This is not a rhetorical
question; I thought it to be true, but I see that there is still code
for faac in decode_fill(); maybe I misremember.)
- Andreas
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next prev parent reply other threads:[~2023-09-12 7:43 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-09-12 6:10 Lynne
[not found] ` <Ne7-l4q--3-9@lynne.ee-Ne7-pA6----9>
2023-09-12 6:11 ` [FFmpeg-devel] [RFC PATCH 2/3] decode: allow decoders to override skip_samples Lynne
2023-09-12 6:14 ` [FFmpeg-devel] [RFC PATCH 3/3] aacdec: allow to skip sbr start-up delay Lynne
[not found] ` <Ne70gnX--3-9@lynne.ee-Ne70juu----9>
2023-09-12 6:15 ` Lynne
2023-09-12 7:10 ` Andreas Rheinhardt [this message]
2023-09-12 16:25 ` [FFmpeg-devel] [RFC PATCH 1/3] aacdec: always skip the first 2048 samples if there's no side data Lynne
2023-09-12 21:24 ` Thierry Foucu
2023-10-03 4:09 ` Lynne
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