Re: [FFmpeg-devel] [PATCH 01/10] avformat/segment: Add segment_write_temp option

["softworkz ." <softworkz-at-hotmail.com@ffmpeg.org>]

> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of
> Marton Balint
> Sent: Samstag, 14. Juni 2025 00:07
> To: FFmpeg development discussions and patches <ffmpeg-
> devel@ffmpeg.org>
> Subject: Re: [FFmpeg-devel] [PATCH 01/10] avformat/segment: Add
> segment_write_temp option
> 
> 
> 
> On Fri, 13 Jun 2025, softworkz . wrote:
> 
> > Hi Marton,
> >
> >
> >> -----Original Message-----
> >> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf
> Of
> >> Marton Balint
> >> Sent: Freitag, 13. Juni 2025 22:38
> >> To: FFmpeg development discussions and patches <ffmpeg-
> >> devel@ffmpeg.org>
> >> Subject: Re: [FFmpeg-devel] [PATCH 01/10] avformat/segment: Add
> >> segment_write_temp option
> >>
> >>
> >>
> >> On Fri, 13 Jun 2025, softworkz wrote:
> >>
> >>> From: softworkz <softworkz@hotmail.com>
> >>>
> >>> Allows to write segments as temp files (.tmp) which
> >>> are renamed on completion.
> >>>
> >>> Signed-off-by: softworkz <softworkz@hotmail.com>
> >>> ---
> >>> libavformat/segment.c | 30 +++++++++++++++++++++++++++---
> >>> 1 file changed, 27 insertions(+), 3 deletions(-)
> >>>
> >>> diff --git a/libavformat/segment.c b/libavformat/segment.c
> >>> index 65323ec678..04e973a198 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 +227,15 @@ 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) {
> >>> +        av_strlcatf(buf, sizeof(buf), ".tmp");
> >>> +        char *temp_name = av_strdup(buf);
> >>> +        if (!temp_name)
> >>> +            return AVERROR(ENOMEM);
> >>
> >> You should use av_asprintf() directly instead of strlcatf() +
> >> av_strdup()
> >
> > I could be wrong, but I was thinking that this way is more
> efficient,
> > because in the av_strdup case, the size of the needed allocation
> is
> > already known, while I would suppose that av_asprintf() needs to
> > allocate a larger size of memory because it cannot predict the
> eventual
> > size after applying all the formats. Am I on a wrong track?
> 
> I think it does not matter, this is not performance critical code,
> so
> simplicity/readability is more imporant. Also we should avoid hard
> coded
> path length limits if we can, an by using a static buffer you can
> hit
> that.

I agree. Yet, the buffer was there already and I just added on to 
that. I can change it to an AVBPrint, but it should probably be
a separate commit I suppose?

First the buffer substitution and then my change?


Thanks,
sw
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