[FFmpeg-devel] [PATCH] avformat/dashenc: Only use temporary files when outputting to file protocol

[Steven Liu]

2017-02-14 21:14 GMT+08:00 Thomas Stephens <thomas at ustudio.com>:

> Has anybody had a chance to look at this patch?
>
> Thanks,
> --Thomas
>
> On Tue, Feb 7, 2017, 2:20 PM Thomas Stephens <thomas at ustudio.com> wrote:
>
> > Skips using temporary files when outputting to a protocol other than
> > "file", which enables dash to output content over network
> > protocols. The logic has been copied from the HLS format.
> > ---
> >  libavformat/dashenc.c | 29 +++++++++++++++++++++++------
> >  1 file changed, 23 insertions(+), 6 deletions(-)
> >
> > diff --git a/libavformat/dashenc.c b/libavformat/dashenc.c
> > index 534fa75..fa56505 100644
> > --- a/libavformat/dashenc.c
> > +++ b/libavformat/dashenc.c
> > @@ -444,9 +444,15 @@ static int write_manifest(AVFormatContext *s, int
> > final)
> >      AVIOContext *out;
> >      char temp_filename[1024];
> >      int ret, i;
> > +    const char *proto = avio_find_protocol_name(s->filename);
> > +    int use_rename = proto && !strcmp(proto, "file");
> > +    static unsigned int warned_non_file = 0;
> >      AVDictionaryEntry *title = av_dict_get(s->metadata, "title", NULL,
> 0);
> >
> > -    snprintf(temp_filename, sizeof(temp_filename), "%s.tmp",
> s->filename);
> > +    if (!use_rename && !warned_non_file++)
> > +        av_log(s, AV_LOG_ERROR, "Cannot use rename on non file protocol,
> > this may lead to races and temporary partial files\n");
> > +
> > +    snprintf(temp_filename, sizeof(temp_filename), use_rename ? "%s.tmp"
> > : "%s", s->filename);
> >      ret = s->io_open(s, &out, temp_filename, AVIO_FLAG_WRITE, NULL);
> >      if (ret < 0) {
> >          av_log(s, AV_LOG_ERROR, "Unable to open %s for writing\n",
> > temp_filename);
> > @@ -548,7 +554,11 @@ static int write_manifest(AVFormatContext *s, int
> > final)
> >      avio_printf(out, "</MPD>\n");
> >      avio_flush(out);
> >      ff_format_io_close(s, &out);
> > -    return avpriv_io_move(temp_filename, s->filename);
> > +
> > +    if (use_rename)
> > +        return avpriv_io_move(temp_filename, s->filename);
> > +
> > +    return 0;
> >  }
> >
> >  static int dash_init(AVFormatContext *s)
> > @@ -796,6 +806,10 @@ static int dash_flush(AVFormatContext *s, int final,
> > int stream)
> >  {
> >      DASHContext *c = s->priv_data;
> >      int i, ret = 0;
> > +
> > +    const char *proto = avio_find_protocol_name(s->filename);
> > +    int use_rename = proto && !strcmp(proto, "file");
> > +
> >      int cur_flush_segment_index = 0;
> >      if (stream >= 0)
> >          cur_flush_segment_index = c->streams[stream].segment_index;
> > @@ -833,7 +847,7 @@ static int dash_flush(AVFormatContext *s, int final,
> > int stream)
> >          if (!c->single_file) {
> >              dash_fill_tmpl_params(filename, sizeof(filename),
> > c->media_seg_name, i, os->segment_index, os->bit_rate, os->start_pts);
> >              snprintf(full_path, sizeof(full_path), "%s%s", c->dirname,
> > filename);
> > -            snprintf(temp_path, sizeof(temp_path), "%s.tmp", full_path);
> > +            snprintf(temp_path, sizeof(temp_path), use_rename ? "%s.tmp"
> > : "%s", full_path);
> >              ret = s->io_open(s, &os->out, temp_path, AVIO_FLAG_WRITE,
> > NULL);
> >              if (ret < 0)
> >                  break;
> > @@ -851,9 +865,12 @@ static int dash_flush(AVFormatContext *s, int final,
> > int stream)
> >              find_index_range(s, full_path, start_pos, &index_length);
> >          } else {
> >              ff_format_io_close(s, &os->out);
> > -            ret = avpriv_io_move(temp_path, full_path);
> > -            if (ret < 0)
> > -                break;
> > +
> > +            if (use_rename) {
> > +                ret = avpriv_io_move(temp_path, full_path);
> > +                if (ret < 0)
> > +                    break;
> > +            }
> >          }
> >          add_segment(os, filename, os->start_pts, os->max_pts -
> > os->start_pts, start_pos, range_length, index_length);
> >          av_log(s, AV_LOG_VERBOSE, "Representation %d media segment %d
> > written to: %s\n", i, os->segment_index, full_path);
> > --
> > 2.5.0
> >
> >
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>


LGTM


and looks like segments, hlsenc