* [FFmpeg-devel] [PATCH] libavformat/mov.c: fix seek issues for fragmented mp4 files
@ 2025-01-28 1:20 Srikanth Kiran Kotagiri
2025-01-28 17:29 ` Srikanth Kotagiri
0 siblings, 1 reply; 3+ messages in thread
From: Srikanth Kiran Kotagiri @ 2025-01-28 1:20 UTC (permalink / raw)
To: ffmpeg-devel
For Fragmented MP4 files where the audio and video streams are written to seperate fragments, the -ss option will cause the file pointer to be set to the first available fragment. This is due to an interaction in search_frag_timestamp() function and get_frag_time() functions.
With this change, we first verify that the fragment does not actually contain the requested fragment before just sending AV_NOPTS_VALUE.
---
libavformat/mov.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/libavformat/mov.c b/libavformat/mov.c
index c016ce8e41..f3e4f4deff 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -87,6 +87,7 @@ typedef struct 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 int mov_switch_root(AVFormatContext *s, int64_t target, int index);
static int mov_metadata_track_or_disc_number(MOVContext *c, AVIOContext *pb,
unsigned len, const char *key)
@@ -1680,6 +1681,27 @@ static int64_t get_frag_time(AVFormatContext *s, AVStream *dst_st,
return frag_stream_info->sidx_pts;
}
+
+ // Check if the requested stream is present in the fragment
+ int stream_present = 0;
+ for (i = 0; i < frag_index->item[index].nb_stream_info; i++) {
+ if (dst_st->id != frag_index->item[index].stream_info[i].id)
+ continue;
+ if ( get_stream_info_time(&frag_index->item[index].stream_info[i]) != AV_NOPTS_VALUE) {
+ exists = 1;
+ break;
+ }
+ if ( mov_switch_root(s,-1,index) < 0)
+ return AV_NOPTS_VALUE;
+ if ( get_stream_info_time(&frag_index->item[index].stream_info[i]) != AV_NOPTS_VALUE) {
+ exists = 1;
+ break;
+ }
+ }
+ if (!stream_present)
+ return AV_NOPTS_VALUE;
+
+
for (i = 0; i < frag_index->item[index].nb_stream_info; i++) {
AVStream *frag_stream = NULL;
frag_stream_info = &frag_index->item[index].stream_info[i];
--
2.39.5 (Apple Git-154)
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^ permalink raw reply [flat|nested] 3+ messages in thread* Re: [FFmpeg-devel] [PATCH] libavformat/mov.c: fix seek issues for fragmented mp4 files
2025-01-28 1:20 [FFmpeg-devel] [PATCH] libavformat/mov.c: fix seek issues for fragmented mp4 files Srikanth Kiran Kotagiri
@ 2025-01-28 17:29 ` Srikanth Kotagiri
0 siblings, 0 replies; 3+ messages in thread
From: Srikanth Kotagiri @ 2025-01-28 17:29 UTC (permalink / raw)
To: ffmpeg-devel
please ignore this patch. I will submit a corrected one.
On Mon, Jan 27, 2025 at 5:20 PM Srikanth Kiran Kotagiri
<srikanthk@gmail.com> wrote:
>
> For Fragmented MP4 files where the audio and video streams are written to seperate fragments, the -ss option will cause the file pointer to be set to the first available fragment. This is due to an interaction in search_frag_timestamp() function and get_frag_time() functions.
>
> With this change, we first verify that the fragment does not actually contain the requested fragment before just sending AV_NOPTS_VALUE.
> ---
> libavformat/mov.c | 22 ++++++++++++++++++++++
> 1 file changed, 22 insertions(+)
>
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index c016ce8e41..f3e4f4deff 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -87,6 +87,7 @@ typedef struct 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 int mov_switch_root(AVFormatContext *s, int64_t target, int index);
>
> static int mov_metadata_track_or_disc_number(MOVContext *c, AVIOContext *pb,
> unsigned len, const char *key)
> @@ -1680,6 +1681,27 @@ static int64_t get_frag_time(AVFormatContext *s, AVStream *dst_st,
> return frag_stream_info->sidx_pts;
> }
>
> +
> + // Check if the requested stream is present in the fragment
> + int stream_present = 0;
> + for (i = 0; i < frag_index->item[index].nb_stream_info; i++) {
> + if (dst_st->id != frag_index->item[index].stream_info[i].id)
> + continue;
> + if ( get_stream_info_time(&frag_index->item[index].stream_info[i]) != AV_NOPTS_VALUE) {
> + exists = 1;
> + break;
> + }
> + if ( mov_switch_root(s,-1,index) < 0)
> + return AV_NOPTS_VALUE;
> + if ( get_stream_info_time(&frag_index->item[index].stream_info[i]) != AV_NOPTS_VALUE) {
> + exists = 1;
> + break;
> + }
> + }
> + if (!stream_present)
> + return AV_NOPTS_VALUE;
> +
> +
> for (i = 0; i < frag_index->item[index].nb_stream_info; i++) {
> AVStream *frag_stream = NULL;
> frag_stream_info = &frag_index->item[index].stream_info[i];
> --
> 2.39.5 (Apple Git-154)
>
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^ permalink raw reply [flat|nested] 3+ messages in thread
* [FFmpeg-devel] [PATCH] libavformat/mov.c: fix seek issues for fragmented mp4 files
@ 2025-01-28 17:32 Srikanth Kiran Kotagiri
0 siblings, 0 replies; 3+ messages in thread
From: Srikanth Kiran Kotagiri @ 2025-01-28 17:32 UTC (permalink / raw)
To: ffmpeg-devel; +Cc: Srikanth Kiran Kotagiri
From: Srikanth Kiran Kotagiri <srikanth@descript.com>
For Fragmented MP4 files where the audio and video streams are written to seperate fragments, the -ss option will cause the file pointer to be set to the first available fragment. This is due to an interaction in search_frag_timestamp() function and get_frag_time() functions.
With this change, we first verify that the fragment does not actually contain the requested fragment before just sending AV_NOPTS_VALUE.
---
libavformat/mov.c | 23 +++++++++++++++++++++++
1 file changed, 23 insertions(+)
diff --git a/libavformat/mov.c b/libavformat/mov.c
index c016ce8e41..c50e6ee35b 100644
--- a/libavformat/mov.c
+++ b/libavformat/mov.c
@@ -87,6 +87,7 @@ typedef struct 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 int mov_switch_root(AVFormatContext *s, int64_t target, int index);
static int mov_metadata_track_or_disc_number(MOVContext *c, AVIOContext *pb,
unsigned len, const char *key)
@@ -1666,6 +1667,7 @@ static int64_t get_frag_time(AVFormatContext *s, AVStream *dst_st,
MOVStreamContext *sc = dst_st->priv_data;
int64_t timestamp;
int i, j;
+ int stream_present;
// If the stream is referenced by any sidx, limit the search
// to fragments that referenced this stream in the sidx
@@ -1680,6 +1682,27 @@ static int64_t get_frag_time(AVFormatContext *s, AVStream *dst_st,
return frag_stream_info->sidx_pts;
}
+
+ // Check if the requested stream is present in the fragment
+ stream_present = 0;
+ for (i = 0; i < frag_index->item[index].nb_stream_info; i++) {
+ if (dst_st->id != frag_index->item[index].stream_info[i].id)
+ continue;
+ if ( get_stream_info_time(&frag_index->item[index].stream_info[i]) != AV_NOPTS_VALUE) {
+ stream_present = 1;
+ break;
+ }
+ if ( mov_switch_root(s,-1,index) < 0)
+ return AV_NOPTS_VALUE;
+ if ( get_stream_info_time(&frag_index->item[index].stream_info[i]) != AV_NOPTS_VALUE) {
+ stream_present = 1;
+ break;
+ }
+ }
+ if (!stream_present)
+ return AV_NOPTS_VALUE;
+
+
for (i = 0; i < frag_index->item[index].nb_stream_info; i++) {
AVStream *frag_stream = NULL;
frag_stream_info = &frag_index->item[index].stream_info[i];
--
2.39.5 (Apple Git-154)
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^ permalink raw reply [flat|nested] 3+ messages in thread
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2025-01-28 1:20 [FFmpeg-devel] [PATCH] libavformat/mov.c: fix seek issues for fragmented mp4 files Srikanth Kiran Kotagiri
2025-01-28 17:29 ` Srikanth Kotagiri
2025-01-28 17:32 Srikanth Kiran Kotagiri
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