Hi all,
Would it be possible to continue the discussion began there ?
http://ffmpeg.org/pipermail/ffmpeg-devel/2015-February/168248.html
The current behavior of FFmpeg when it comes to manage FLAC tags with
both vorbis tags and ID3 tags is to append both, which leads to, for
example, "Artist: Pink Floyd;Pink Floyd" in FFprobe. This is not a
desired output: as the XIPH faq says about FLAC
(https://xiph.org/flac/faq.html):
"FLAC has it's own native tagging system which is identical to that of
Vorbis. They are called alternately "FLAC tags" and "Vorbis comments".
It is the only tagging system required and guaranteed to be supported by
FLAC implementations.
Out of convenience, the reference decoder knows how to skip ID3 tags so
that they don't interfere with decoding. But you should not expect any
tags beside FLAC tags to be supported in applications; some
implementations may not even be able to decode a FLAC file with ID3 tags."
This issue was also submitted here https://trac.ffmpeg.org/ticket/3799,
but still discuted in the above thread.
Ben Boeckel made the attached patch (which I edited a bit to fit FFmpeg
last version), which fixes the issue.
The problem that remained was that many other files could have
irrelevant id3v2 tags, not only Vorbis/FLAC files, so another more
global patch may be needed to fix that definitely.
So, do you think Ben's patch could be merged "as-is", or does it only
raise more questions?
Regards,
Paul
>From b10a32fecf05b17f6e824b662b7db07bff195d2d Mon Sep 17 00:00:00 2001
From: Paul Arzelier <paul.arzel...@free.fr>
Date: Wed, 25 Jan 2017 18:55:52 +0100
Subject: [PATCH] Fixed behavior when id3 tags were found on FLAC files
Originally-by: Ben Boeckel <maths...@gmail.com>
---
libavformat/flacdec.c | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)
diff --git a/libavformat/flacdec.c b/libavformat/flacdec.c
index 3060dc45fd..f8d4611398 100644
--- a/libavformat/flacdec.c
+++ b/libavformat/flacdec.c
@@ -48,6 +48,7 @@ static int flac_read_header(AVFormatContext *s)
int ret, metadata_last=0, metadata_type, metadata_size, found_streaminfo=0;
uint8_t header[4];
uint8_t *buffer=NULL;
+ int has_id3 = 0;
FLACDecContext *flac = s->priv_data;
AVStream *st = avformat_new_stream(s, NULL);
if (!st)
@@ -63,6 +64,22 @@ static int flac_read_header(AVFormatContext *s)
return 0;
}
+ if (av_dict_count(s->metadata)) {
+ /* XXX: Is there a better way to parse this out? ID3 parsing is done
+ * all the way out in avformat_open_input. */
+ has_id3 = 1;
+ }
+
+ if (has_id3) {
+ int level = AV_LOG_WARNING;
+ if (s->error_recognition & AV_EF_COMPLIANT)
+ level = AV_LOG_ERROR;
+ av_log(s, level, "Spec-compliant flac files do not support ID3 tags.\n");
+ if (s->error_recognition & AV_EF_EXPLODE)
+ return AVERROR_INVALIDDATA;
+ }
+
+
/* process metadata blocks */
while (!avio_feof(s->pb) && !metadata_last) {
avio_read(s->pb, header, 4);
@@ -172,8 +189,17 @@ static int flac_read_header(AVFormatContext *s)
}
/* process supported blocks other than STREAMINFO */
if (metadata_type == FLAC_METADATA_TYPE_VORBIS_COMMENT) {
+ AVDictionary *other_meta = NULL;
AVDictionaryEntry *chmask;
+ if (has_id3) {
+ av_log(s, AV_LOG_VERBOSE, "FLAC found with ID3 and vorbis tags; ignoring ID3 tags also provided by vorbis.\n");
+
+ other_meta = s->metadata;
+ s->metadata = NULL;
+ }
+
ret = ff_vorbis_comment(s, &s->metadata, buffer, metadata_size, 1);
if (ret < 0) {
av_log(s, AV_LOG_WARNING, "error parsing VorbisComment metadata\n");
@@ -181,6 +207,11 @@ static int flac_read_header(AVFormatContext *s)
s->event_flags |= AVFMT_EVENT_FLAG_METADATA_UPDATED;
}
+ if (other_meta) {
+ av_dict_copy(&s->metadata, other_meta, AV_DICT_DONT_OVERWRITE);
+ av_dict_free(&other_meta);
+ }
+
/* parse the channels mask if present */
chmask = av_dict_get(s->metadata, "WAVEFORMATEXTENSIBLE_CHANNEL_MASK", NULL, 0);
if (chmask) {
--
2.11.0
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