Utility function to report seekability features for a given input.
Useful for ffprobe and to extend seek possibilities in fftools.
---
v2:
made constants more descriptive
add exception for rtsp false negative seekability
doc/APIchanges | 3 +++
libavformat/avformat.h | 22 ++++++++++++++++++
libavformat/seek.c | 53 ++++++++++++++++++++++++++++++++++++++++++
libavformat/version.h | 2 +-
4 files changed, 79 insertions(+), 1 deletion(-)
diff --git a/doc/APIchanges b/doc/APIchanges
index 65bf5a9419..879f56b572 100644
--- a/doc/APIchanges
+++ b/doc/APIchanges
@@ -2,6 +2,9 @@ The last version increases of all libraries were on 2025-03-28
API changes, most recent first:
+2025-04-xx - xxxxxxxxxx - lavf 62.1.100 - avformat.h
+ Add avformat_query_seekable().
+
2025-04-07 - 19e9a203b7 - lavu 60.01.100 - dict.h
Add AV_DICT_DEDUP.
diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index 498c3020a5..f9da5e9e79 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -2338,6 +2338,28 @@ int av_seek_frame(AVFormatContext *s, int stream_index,
int64_t timestamp,
*/
int avformat_seek_file(AVFormatContext *s, int stream_index, int64_t min_ts,
int64_t ts, int64_t max_ts, int flags);
+#define AVSEEKABLE_IO_NORMAL 0x00000001 ///< I/O is seekable like a
local file
+#define AVSEEKABLE_IO_PROTOCOL 0x00000002 ///< I/O seek is through
protocol request via avio_seek_time
+#define AVSEEKABLE_VIA_DEMUXER 0x00000004 ///< demuxer has a seek function
+#define AVSEEKABLE_VIA_PKTSCAN 0x00000008 ///< seek is performed by
consuming and scanning packet timestamps
+#define AVSEEKABLE_BY_TIME 0x00000100 ///< seek target can be a
timestamp
+#define AVSEEKABLE_BY_BYTE 0x00000200 ///< seek target can be in bytes
+#define AVSEEKABLE_BY_FRAME 0x00000400 ///< seek target can be a frame
index
+#define AVSEEKABLE_PROP_PTS 0x00010000 ///< seek target timestamp is
expected to be PTS
+#define AVSEEKABLE_PROP_FAST 0x00020000 ///< demuxer allows fast but
inaccurate seeking
+#define AVSEEKABLE_PROP_FWDONLY 0x00040000 ///< set seek will be equal or
forward of specified seek point
+
+/**
+ * Report if and how a seek can be performed in a given input.
+ *
+ * @param s media file handle
+ *
+ * @return 0 if no seek can be performed on input,
+ * -1 if the fmt ctx is NULL or is not an input
+ * else return AVSEEKABLE_ bitflags indicating seekability features.
+ */
+int avformat_query_seekable(AVFormatContext *s);
+
/**
* Discard all internally buffered data. This can be useful when dealing with
* discontinuities in the byte stream. Generally works only with formats that
diff --git a/libavformat/seek.c b/libavformat/seek.c
index c0d94371e6..8be1bdec30 100644
--- a/libavformat/seek.c
+++ b/libavformat/seek.c
@@ -712,6 +712,59 @@ int avformat_seek_file(AVFormatContext *s, int
stream_index, int64_t min_ts,
return ret;
}
+int avformat_query_seekable(AVFormatContext *s)
+{
+ int ret = 0;
+
+ if (!s || !s->iformat)
+ return -1;
+
+ if ( strcmp(s->iformat->name, "rtsp") && (!(s->pb && s->pb->seekable) ||
s->ctx_flags & AVFMTCTX_UNSEEKABLE) )
+ return 0;
+
+ if (s->pb->seekable & AVIO_SEEKABLE_NORMAL)
+ ret |= AVSEEKABLE_IO_NORMAL;
+
+ if (s->pb->seekable & AVIO_SEEKABLE_TIME)
+ ret |= AVSEEKABLE_IO_PROTOCOL;
+
+ if (ffifmt(s->iformat)->read_seek || ffifmt(s->iformat)->read_seek2)
+ ret |= AVSEEKABLE_VIA_DEMUXER;
+
+ if (ffifmt(s->iformat)->read_timestamp && !(s->iformat->flags &
AVFMT_NOBINSEARCH))
+ ret |= AVSEEKABLE_VIA_PKTSCAN;
+
+ if (!(s->iformat->flags & AVFMT_NOTIMESTAMPS))
+ ret |= AVSEEKABLE_BY_TIME;
+
+ // TODO: incomplete, a few demuxers don't set flag but error out on byte
seek
+ if (!(s->iformat->flags & AVFMT_NO_BYTE_SEEK))
+ ret |= AVSEEKABLE_BY_BYTE;
+
+ // TODO: no flag for frame seeking. Add flag and enable this check
+ if (s->iformat->flags & 0)
+ ret |= AVSEEKABLE_BY_FRAME;
+
+ if (s->iformat->flags & AVFMT_SEEK_TO_PTS)
+ ret |= AVSEEKABLE_PROP_PTS;
+
+ // TODO: flag exists but not added to the demuxers which support it
+ if (s->iformat->flags & AVFMT_FLAG_FAST_SEEK)
+ ret |= AVSEEKABLE_PROP_FAST;
+
+ if (!(ret & AVSEEKABLE_VIA_DEMUXER) && ret & AVSEEKABLE_VIA_PKTSCAN)
+ ret |= AVSEEKABLE_PROP_FWDONLY;
+
+ if ( !(ret & AVSEEKABLE_VIA_DEMUXER) &&
+ !(ret & AVSEEKABLE_VIA_PKTSCAN) &&
+ !(ret & AVSEEKABLE_BY_BYTE) &&
+ !(ret & AVSEEKABLE_IO_PROTOCOL) &&
+ (s->iformat->flags & AVFMT_NOGENSEARCH) )
+ ret = 0;
+
+ return ret;
+}
+
/** Flush the frame reader. */
void ff_read_frame_flush(AVFormatContext *s)
{
diff --git a/libavformat/version.h b/libavformat/version.h
index 752aac16f7..a7c80dc564 100644
--- a/libavformat/version.h
+++ b/libavformat/version.h
@@ -31,7 +31,7 @@
#include "version_major.h"
-#define LIBAVFORMAT_VERSION_MINOR 0
+#define LIBAVFORMAT_VERSION_MINOR 1
#define LIBAVFORMAT_VERSION_MICRO 100
#define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
--
2.49.0
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