[FFmpeg-devel] [PATCH v2 1/6] avformat/segment: Add segment_write_temp option

[softworkz]

From: softworkz <softworkz at hotmail.com>

Allows to write segments as temp files (.tmp) which
are renamed on completion.

Signed-off-by: softworkz <softworkz at hotmail.com>
---
 doc/muxers.texi       |  5 +++++
 libavformat/segment.c | 29 ++++++++++++++++++++++++++---
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/doc/muxers.texi b/doc/muxers.texi
index 30c95c3d34..6d5c17b4cc 100644
--- a/doc/muxers.texi
+++ b/doc/muxers.texi
@@ -3505,6 +3505,11 @@ argument must be a time duration specification, and defaults to 0.
 If enabled, write an empty segment if there are no packets during the period a
 segment would usually span. Otherwise, the segment will be filled with the next
 packet written. Defaults to @code{0}.
+
+ at item segment_write_temp @var{1|0}
+Write segments to files with a .tmp extension. Each file is renamed to its 
+actual name on completion. This can help to prevent segment files from 
+being accessed before they are complete. Disabled by default (@code{0}).
 @end table
 
 Make sure to require a closed GOP when encoding and to set the GOP
diff --git a/libavformat/segment.c b/libavformat/segment.c
index 65323ec678..14eba90292 100644
--- a/libavformat/segment.c
+++ b/libavformat/segment.c
@@ -121,6 +121,7 @@ typedef struct SegmentContext {
     int   break_non_keyframes;
     int   write_empty;
 
+    int segment_write_temp; ///< write segments as temp files and rename on completion
     int use_rename;
     char temp_list_filename[1024];
 
@@ -226,6 +227,14 @@ static int set_segment_filename(AVFormatContext *s)
              seg->entry_prefix ? seg->entry_prefix : "",
              av_basename(oc->url));
 
+    // Write segment as a temp file and rename on completion
+    if(seg->segment_write_temp) {
+        char *temp_name = av_asprintf("%s%s", buf, ".tmp");
+        if (!temp_name)
+            return AVERROR(ENOMEM);
+        ff_format_set_url(oc, temp_name);
+    }
+
     return 0;
 }
 
@@ -372,7 +381,7 @@ static int segment_end(AVFormatContext *s, int write_trailer, int is_last)
             SegmentListEntry *entry = av_mallocz(sizeof(*entry));
             if (!entry) {
                 ret = AVERROR(ENOMEM);
-                goto end;
+                goto fail;
             }
 
             /* append new element */
@@ -393,7 +402,7 @@ static int segment_end(AVFormatContext *s, int write_trailer, int is_last)
             }
 
             if ((ret = segment_list_open(s)) < 0)
-                goto end;
+                goto fail;
             for (entry = seg->segment_list_entries; entry; entry = entry->next)
                 segment_list_print_entry(seg->list_pb, seg->list_type, entry, s);
             if (seg->list_type == LIST_TYPE_M3U8 && is_last)
@@ -450,7 +459,20 @@ static int segment_end(AVFormatContext *s, int write_trailer, int is_last)
         }
     }
 
-end:
+    ff_format_io_close(oc, &oc->pb);
+
+    // Now rename the .tmp file to its actual name.
+    if (seg->segment_write_temp) {
+        char *final_filename = av_strndup(oc->url, strlen(oc->url) - 4);
+        if (!final_filename)
+            return AVERROR(ENOMEM);
+        ret = ff_rename(oc->url, final_filename, s);
+        av_free(final_filename);
+    }
+
+    return ret;
+
+fail:
     ff_format_io_close(oc, &oc->pb);
 
     return ret;
@@ -1075,6 +1097,7 @@ static const AVOption options[] = {
     { "reset_timestamps", "reset timestamps at the beginning of each segment", OFFSET(reset_timestamps), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, E },
     { "initial_offset", "set initial timestamp offset", OFFSET(initial_offset), AV_OPT_TYPE_DURATION, {.i64 = 0}, -INT64_MAX, INT64_MAX, E },
     { "write_empty_segments", "allow writing empty 'filler' segments", OFFSET(write_empty), AV_OPT_TYPE_BOOL, {.i64 = 0}, 0, 1, E },
+    { "segment_write_temp", "write segments as temp files (.tmp) and rename on completion", OFFSET(segment_write_temp), AV_OPT_TYPE_BOOL,   {.i64 = 0}, 0, 1, E }, 
     { NULL },
 };
 
-- 
ffmpeg-codebot