[FFmpeg-devel] [PATCHv2] avformat/file: add seekable option to disallow seeking

[Marton Balint]

v2: Disallow positive override of seekability as requested by Hendrik Leppkes.

Signed-off-by: Marton Balint <cus at passwd.hu>
---
 doc/protocols.texi | 8 ++++++++
 libavformat/file.c | 5 +++++
 2 files changed, 13 insertions(+)

diff --git a/doc/protocols.texi b/doc/protocols.texi
index e1caa049a5..3e4e7af3d4 100644
--- a/doc/protocols.texi
+++ b/doc/protocols.texi
@@ -199,6 +199,14 @@ If set to 1, the protocol will retry reading at the end of the file, allowing
 reading files that still are being written. In order for this to terminate,
 you either need to use the rw_timeout option, or use the interrupt callback
 (for API users).
+
+ at item seekable
+Controls if seekability is advertised on the file. 0 means non-seekable, -1
+means auto (seekable for normal files, non-seekable for named pipes).
+
+Many demuxers handle seekable and non-seekable resources differently,
+overriding this might speed up opening certain files at the cost of losing some
+features (e.g. accurate seeking).
 @end table
 
 @section ftp
diff --git a/libavformat/file.c b/libavformat/file.c
index e613b91010..08c7f8e6dd 100644
--- a/libavformat/file.c
+++ b/libavformat/file.c
@@ -73,6 +73,7 @@ typedef struct FileContext {
     int trunc;
     int blocksize;
     int follow;
+    int seekable;
 #if HAVE_DIRENT_H
     DIR *dir;
 #endif
@@ -82,6 +83,7 @@ static const AVOption file_options[] = {
     { "truncate", "truncate existing files on write", offsetof(FileContext, trunc), AV_OPT_TYPE_BOOL, { .i64 = 1 }, 0, 1, AV_OPT_FLAG_ENCODING_PARAM },
     { "blocksize", "set I/O operation maximum block size", offsetof(FileContext, blocksize), AV_OPT_TYPE_INT, { .i64 = INT_MAX }, 1, INT_MAX, AV_OPT_FLAG_ENCODING_PARAM },
     { "follow", "Follow a file as it is being written", offsetof(FileContext, follow), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, AV_OPT_FLAG_DECODING_PARAM },
+    { "seekable", "Sets if the file is seekable", offsetof(FileContext, seekable), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, 0, AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_ENCODING_PARAM },
     { NULL }
 };
 
@@ -238,6 +240,9 @@ static int file_open(URLContext *h, const char *filename, int flags)
     if (!h->is_streamed && flags & AVIO_FLAG_WRITE)
         h->min_packet_size = h->max_packet_size = 262144;
 
+    if (c->seekable >= 0)
+        h->is_streamed = !c->seekable;
+
     return 0;
 }
 
-- 
2.16.4