[FFmpeg-devel] [PATCH] WIP: fix-heaac-probe (PR #20239)

[ngaullier <code@ffmpeg.org>]

PR #20239 opened by ngaullier
URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20239
Patch URL: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/20239.patch

(Sent it yesterday on ML but forgot to rebase... Switch to forgejo now since it seems preferred).
History:
v4-forgejo: rebased
v4 (Michael): first patch splitted: now 3 patches, code is unchanged.
v3 (James): complete overhaul of the commit message of the first
patch, code is unchanged. Second patch is fully unchanged ("should be ok").
v2 (Baptiste): keep setting the profile in the parser even if it is not
always reliable, just allow it to be overriden by the decoder.


From e75fc89b2a69375ad8d47e384fdaa63dfb579e3e Mon Sep 17 00:00:00 2001
From: Nicolas Gaullier <nicolas.gaullier@cji.paris>
Date: Tue, 12 Aug 2025 12:09:02 +0200
Subject: [PATCH 1/3] avcodec/aac_ac3_parser: remove unused USAC/ADTS code

ff_adts_header_parse() parse the object_type from a 2 bits field.
See also 696ea1c2236842572df88d573e24a39be3f19c98.

Partially reverts 64bb91fd3b5a00a8849531c7e8dd207f2a626096.

Signed-off-by: Nicolas Gaullier <nicolas.gaullier@cji.paris>
---
 libavcodec/aac_ac3_parser.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libavcodec/aac_ac3_parser.c b/libavcodec/aac_ac3_parser.c
index e10ce13a3b..ced640dd28 100644
--- a/libavcodec/aac_ac3_parser.c
+++ b/libavcodec/aac_ac3_parser.c
@@ -155,7 +155,8 @@ get_next:
                 return i;
 
             avctx->profile = hdr.object_type - 1;
-            s1->key_frame = (avctx->profile == AV_PROFILE_AAC_USAC) ? get_bits1(&gb) : 1;
+            /* ADTS does not support USAC */
+            s1->key_frame = 1;
             bit_rate = hdr.bit_rate;
 #endif
         }
-- 
2.49.1


From 49c89a1771634fd68d8530d62495f835c505a1f0 Mon Sep 17 00:00:00 2001
From: Nicolas Gaullier <nicolas.gaullier@cji.paris>
Date: Tue, 12 Aug 2025 12:13:21 +0200
Subject: [PATCH 2/3] avcodec/aac_ac3_parser: simplify

Use ff_adts_header_parse_buf() wrapper to simplify as GetBitContext is
no longer needed (it was introduced for USAC).

Partially reverts 64bb91fd3b5a00a8849531c7e8dd207f2a626096.

Signed-off-by: Nicolas Gaullier <nicolas.gaullier@cji.paris>
---
 libavcodec/aac_ac3_parser.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/libavcodec/aac_ac3_parser.c b/libavcodec/aac_ac3_parser.c
index ced640dd28..b49ce0277c 100644
--- a/libavcodec/aac_ac3_parser.c
+++ b/libavcodec/aac_ac3_parser.c
@@ -147,11 +147,9 @@ get_next:
         } else {
 #if CONFIG_AAC_PARSER
             AACADTSHeaderInfo hdr;
-            GetBitContext gb;
 
-            init_get_bits8(&gb, buf, buf_size);
             if (buf_size < AV_AAC_ADTS_HEADER_SIZE ||
-                ff_adts_header_parse(&gb, &hdr) < 0)
+                ff_adts_header_parse_buf(buf, &hdr) < 0)
                 return i;
 
             avctx->profile = hdr.object_type - 1;
-- 
2.49.1


From b90a2c7e020c46d95045ed9d895b51de4213e458 Mon Sep 17 00:00:00 2001
From: Nicolas Gaullier <nicolas.gaullier@cji.paris>
Date: Mon, 7 Jul 2025 14:50:10 +0200
Subject: [PATCH 3/3] avcodec/aac_ac3_parser: do not override the profile set
 by the decoder

Parsing the ADTS header is not enough to detect HE-AAC v1/v2.

Regression since 64bb91fd3b5a00a8849531c7e8dd207f2a626096.

Fixes #11600

Signed-off-by: Nicolas Gaullier <nicolas.gaullier@cji.paris>
---
 libavcodec/aac_ac3_parser.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/libavcodec/aac_ac3_parser.c b/libavcodec/aac_ac3_parser.c
index b49ce0277c..51c801214c 100644
--- a/libavcodec/aac_ac3_parser.c
+++ b/libavcodec/aac_ac3_parser.c
@@ -152,7 +152,8 @@ get_next:
                 ff_adts_header_parse_buf(buf, &hdr) < 0)
                 return i;
 
-            avctx->profile = hdr.object_type - 1;
+            if (avctx->profile == AV_PROFILE_UNKNOWN)
+                avctx->profile = hdr.object_type - 1;
             /* ADTS does not support USAC */
             s1->key_frame = 1;
             bit_rate = hdr.bit_rate;
-- 
2.49.1

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