This one is perhaps a bit dubious, but on frags.mp4 it saves a seek. I
have no strong feelings on this patch, it just struck me as far simpler
to always read mfra
I checked the ISO/IEC spec and mfra may be present in any file that is
isom branded. Usually it is only present for fragmented files
I also noticed movenc writes moof after mdat rather than before it.
This forces movdec to read more than would otherwise be necessary
/Tomas
From db3d3e7bf6d12493e571506dc85003d5f957e964 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tomas=20H=C3=A4rdin?= <g...@haerdin.se>
Date: Wed, 11 Dec 2024 14:59:10 +0100
Subject: [PATCH 2/3] lavf/mov: Always try to parse mfra
Parsing mfra even before encountering moof saves a seek on some files
---
libavformat/isom.h | 1 -
libavformat/mov.c | 27 ++++++++++-----------------
2 files changed, 10 insertions(+), 18 deletions(-)
diff --git a/libavformat/isom.h b/libavformat/isom.h
index f18b15bbff..e73db77ebe 100644
--- a/libavformat/isom.h
+++ b/libavformat/isom.h
@@ -338,7 +338,6 @@ typedef struct MOVContext {
int bitrates_count;
int moov_retry;
int use_mfra_for;
- int has_looked_for_mfra;
int use_tfdt;
MOVFragmentIndex frag_index;
int atom_depth;
diff --git a/libavformat/mov.c b/libavformat/mov.c
index cfcd64b7db..4f90d03f62 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -85,7 +85,6 @@ typedef struct MOVParseTableEntry {
} MOVParseTableEntry;
static int mov_read_default(MOVContext *c, AVIOContext *pb, MOVAtom atom);
-static int mov_read_mfra(MOVContext *c, AVIOContext *f);
static void mov_free_stream_context(AVFormatContext *s, AVStream *st);
static int64_t add_ctts_entry(MOVCtts** ctts_data, unsigned int* ctts_count, unsigned int* allocated_size,
int count, int duration);
@@ -1804,22 +1803,6 @@ static int mov_read_moof(MOVContext *c, AVIOContext *pb, MOVAtom atom)
{
// Set by mov_read_tfhd(). mov_read_trun() will reject files missing tfhd.
c->fragment.found_tfhd = 0;
-
- if (!c->has_looked_for_mfra) {
- c->has_looked_for_mfra = 1;
- if (pb->seekable & AVIO_SEEKABLE_NORMAL) {
- int ret;
- av_log(c->fc, AV_LOG_VERBOSE, "stream has moof boxes, will look "
- "for a mfra\n");
- if ((ret = mov_read_mfra(c, pb)) < 0) {
- av_log(c->fc, AV_LOG_VERBOSE, "found a moof box but failed to "
- "read the mfra (may be a live ismv)\n");
- }
- } else {
- av_log(c->fc, AV_LOG_VERBOSE, "found a moof box but stream is not "
- "seekable, can not look for mfra\n");
- }
- }
c->fragment.moof_offset = c->fragment.implicit_offset = avio_tell(pb) - 8;
av_log(c->fc, AV_LOG_TRACE, "moof offset %"PRIx64"\n", c->fragment.moof_offset);
c->frag_index.current = update_frag_index(c, c->fragment.moof_offset);
@@ -10509,6 +10492,16 @@ static int mov_read_header(AVFormatContext *s)
else
atom.size = INT64_MAX;
+ if (pb->seekable & AVIO_SEEKABLE_NORMAL) {
+ int ret;
+ av_log(mov->fc, AV_LOG_VERBOSE, "looking for mfra\n");
+ if ((ret = mov_read_mfra(mov, pb)) < 0) {
+ av_log(mov->fc, AV_LOG_VERBOSE, "no mfra found\n");
+ }
+ } else {
+ av_log(mov->fc, AV_LOG_VERBOSE, "file not seekable, will not look for mfra\n");
+ }
+
/* check MOV header */
do {
if (mov->moov_retry)
--
2.39.2
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