From: Timo Rothenpieler via ffmpeg-devel <ffmpeg-devel@ffmpeg.org>
To: ffmpeg-devel@ffmpeg.org
Cc: Timo Rothenpieler <code@ffmpeg.org>
Subject: [FFmpeg-devel] [PR] avcodec/prores_raw: use av_popcount instead of limited lookup table (PR #21505)
Date: Sun, 18 Jan 2026 17:55:01 -0000
Message-ID: <176875890239.25.7496494912959696703@4457048688e7> (raw)
PR #21505 opened by Timo Rothenpieler (BtbN)
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21505
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/21505.patch
The calculation can yield bigger values than the lookup table provides.
So just use actual popcount instead.
Fixes #21503
>From 7379539685ec900b372d87ad25a23e82b8b45f17 Mon Sep 17 00:00:00 2001
From: Timo Rothenpieler <timo@rothenpieler.org>
Date: Sun, 18 Jan 2026 18:52:52 +0100
Subject: [PATCH] avcodec/prores_raw: use av_popcount instead of limited lookup
table
The calculation can yield bigger values than the lookup table provides.
So just use actual popcount instead.
Fixes #21503
---
libavcodec/prores_raw.c | 6 +-----
1 file changed, 1 insertion(+), 5 deletions(-)
diff --git a/libavcodec/prores_raw.c b/libavcodec/prores_raw.c
index 8be566ed36..eb1a9af14f 100644
--- a/libavcodec/prores_raw.c
+++ b/libavcodec/prores_raw.c
@@ -93,10 +93,6 @@ static uint16_t get_value(GetBitContext *gb, int16_t codebook)
#define TODCCODEBOOK(x) ((x + 1) >> 1)
-static const uint8_t align_tile_w[16] = {
- 0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4,
-};
-
#define DC_CB_MAX 12
const uint8_t ff_prores_raw_dc_cb[DC_CB_MAX + 1] = {
0x010, 0x021, 0x032, 0x033, 0x033, 0x033, 0x044, 0x044, 0x044, 0x044, 0x044, 0x044, 0x076,
@@ -432,7 +428,7 @@ static int decode_frame(AVCodecContext *avctx,
s->nb_tw = (w + 15) >> 4;
s->nb_th = (h + 15) >> 4;
- s->nb_tw = (s->nb_tw >> align) + align_tile_w[~(-1 * (1 << align)) & s->nb_tw];
+ s->nb_tw = (s->nb_tw >> align) + av_popcount(~(-1 * (1 << align)) & s->nb_tw);
s->nb_tiles = s->nb_tw * s->nb_th;
av_log(avctx, AV_LOG_DEBUG, "%dx%d | nb_tiles: %d\n", s->nb_tw, s->nb_th, s->nb_tiles);
--
2.52.0
_______________________________________________
ffmpeg-devel mailing list -- ffmpeg-devel@ffmpeg.org
To unsubscribe send an email to ffmpeg-devel-leave@ffmpeg.org
reply other threads:[~2026-01-18 17:55 UTC|newest]
Thread overview: [no followups] expand[flat|nested] mbox.gz Atom feed
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=176875890239.25.7496494912959696703@4457048688e7 \
--to=ffmpeg-devel@ffmpeg.org \
--cc=code@ffmpeg.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Git Inbox Mirror of the ffmpeg-devel mailing list - see https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
This inbox may be cloned and mirrored by anyone:
git clone --mirror https://master.gitmailbox.com/ffmpegdev/0 ffmpegdev/git/0.git
# If you have public-inbox 1.1+ installed, you may
# initialize and index your mirror using the following commands:
public-inbox-init -V2 ffmpegdev ffmpegdev/ https://master.gitmailbox.com/ffmpegdev \
ffmpegdev@gitmailbox.com
public-inbox-index ffmpegdev
Example config snippet for mirrors.
AGPL code for this site: git clone https://public-inbox.org/public-inbox.git