[FFmpeg-devel] [PATCH 1/2 RESEND] avformat/rtsp: set AVFMTCTX_UNSEEKABLE flag

[FFmpeg-devel] [PATCH 1/2 RESEND] avformat/rtsp: set AVFMTCTX_UNSEEKABLE flag

[Kaarle Ritvanen via ffmpeg-devel]

for live RTP streams. Some external applications, such as Qt Multimedia,
depend on this flag being set correctly.

Signed-off-by: Kaarle Ritvanen <kaarle.ritvanen@datakunkku.fi>
---
 libavformat/rtsp.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/libavformat/rtsp.c b/libavformat/rtsp.c
index 5ea471b40c..e7c00c69fa 100644
--- a/libavformat/rtsp.c
+++ b/libavformat/rtsp.c
@@ -629,8 +629,8 @@ static void sdp_parse_line(AVFormatContext *s, SDPParseState *s1,
             rtsp_parse_range_npt(p, &start, &end);
             s->start_time = start;
             /* AV_NOPTS_VALUE means live broadcast (and can't seek) */
-            s->duration   = (end == AV_NOPTS_VALUE) ?
-                            AV_NOPTS_VALUE : end - start;
+            if (end != AV_NOPTS_VALUE)
+                s->duration = end - start;
         } else if (av_strstart(p, "lang:", &p)) {
             if (s->nb_streams > 0) {
                 get_word(buf1, sizeof(buf1), &p);
@@ -720,6 +720,8 @@ int ff_sdp_parse(AVFormatContext *s, const char *content)
     char buf[SDP_MAX_SIZE], *q;
     SDPParseState sdp_parse_state = { { 0 } }, *s1 = &sdp_parse_state;
 
+    s->duration = AV_NOPTS_VALUE;
+
     p = content;
     for (;;) {
         p += strspn(p, SPACE_CHARS);
@@ -753,6 +755,9 @@ int ff_sdp_parse(AVFormatContext *s, const char *content)
         av_freep(&s1->default_exclude_source_addrs[i]);
     av_freep(&s1->default_exclude_source_addrs);
 
+    if (s->duration == AV_NOPTS_VALUE)
+        s->ctx_flags |= AVFMTCTX_UNSEEKABLE;
+
     return 0;
 }
 #endif /* CONFIG_RTPDEC */
-- 
2.49.0

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[FFmpeg-devel] [PATCH 2/2 RESEND] avformat/seek: fail seeking immediately

[Kaarle Ritvanen via ffmpeg-devel]

when AVFMTCTX_UNSEEKABLE is set. Depending on the codec, the execution
of this function may take several seconds. This is an optimization for
the case where the stream is already known unseekable.

Signed-off-by: Kaarle Ritvanen <kaarle.ritvanen@datakunkku.fi>
---
 libavformat/seek.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libavformat/seek.c b/libavformat/seek.c
index c0d94371e6..1a7d3d6741 100644
--- a/libavformat/seek.c
+++ b/libavformat/seek.c
@@ -643,6 +643,9 @@ int av_seek_frame(AVFormatContext *s, int stream_index,
 {
     int ret;
 
+    if (s->ctx_flags & AVFMTCTX_UNSEEKABLE)
+        return AVERROR(ENOSYS);
+
     if (ffifmt(s->iformat)->read_seek2 && !ffifmt(s->iformat)->read_seek) {
         int64_t min_ts = INT64_MIN, max_ts = INT64_MAX;
         if ((flags & AVSEEK_FLAG_BACKWARD))
-- 
2.49.0

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Re: [FFmpeg-devel] [PATCH 2/2 RESEND] avformat/seek: fail seeking immediately

[Zhao Zhili]

> On May 28, 2025, at 20:08, Kaarle Ritvanen via ffmpeg-devel <ffmpeg-devel@ffmpeg.org> wrote:
> 
> when AVFMTCTX_UNSEEKABLE is set. Depending on the codec, the execution
> of this function may take several seconds. This is an optimization for

Why this depending on the codec? Could you provide a case that takes several seconds?

> the case where the stream is already known unseekable.
> 
> Signed-off-by: Kaarle Ritvanen <kaarle.ritvanen@datakunkku.fi>
> ---
> libavformat/seek.c | 3 +++
> 1 file changed, 3 insertions(+)
> 
> diff --git a/libavformat/seek.c b/libavformat/seek.c
> index c0d94371e6..1a7d3d6741 100644
> --- a/libavformat/seek.c
> +++ b/libavformat/seek.c
> @@ -643,6 +643,9 @@ int av_seek_frame(AVFormatContext *s, int stream_index,
> {
>     int ret;
> 
> +    if (s->ctx_flags & AVFMTCTX_UNSEEKABLE)
> +        return AVERROR(ENOSYS);
> +
>     if (ffifmt(s->iformat)->read_seek2 && !ffifmt(s->iformat)->read_seek) {
>         int64_t min_ts = INT64_MIN, max_ts = INT64_MAX;
>         if ((flags & AVSEEK_FLAG_BACKWARD))
> -- 
> 2.49.0
> 
> _______________________________________________
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> ffmpeg-devel@ffmpeg.org
> https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
> 
> To unsubscribe, visit link above, or email
> ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".

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Re: [FFmpeg-devel] [PATCH 2/2 RESEND] avformat/seek: fail seeking immediately

[Kaarle Ritvanen via ffmpeg-devel]

On Wed, 28 May 2025, Zhao Zhili wrote:

> Why this depending on the codec? Could you provide a case that takes 
> several seconds?

I encountered the problem with an RTP live stream using H.264 in 
intra-refresh mode. I think the delay is related to seek_frame_generic 
trying to find keyframes in the stream.

-- 
Kaarle Ritvanen
Data King Ltd
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