[FFmpeg-devel] [PATCH] avformat/assenc: Don't truncate lines to 4095 characters

[Paul B Mahol]

On Sun, Aug 4, 2019 at 2:58 PM Marton Balint <cus at passwd.hu> wrote:

>
>
> On Sun, 4 Aug 2019, Paul B Mahol wrote:
>
> > On Sun, Aug 4, 2019 at 12:54 PM Marton Balint <cus at passwd.hu> wrote:
> >
> >>
> >>
> >> On Sat, 3 Aug 2019, Tellow Krinkle wrote:
> >>
> >> > Fixes #6390
> >> >
> >> > Sample file for new test:
> >>
> https://gist.githubusercontent.com/tellowkrinkle/d6a6e328f892dbbacc000ad9c3890644/raw/4f68e56b1f0fab594aae040723722af4f5161a02/longline.ass
> >> >
> >> > Signed-off-by: Tellow Krinkle <tellowkrinkle at gmail.com>
> >> > ---
> >> > libavformat/assenc.c     | 4 +++-
> >> > tests/fate/subtitles.mak | 4 ++++
> >> > 2 files changed, 7 insertions(+), 1 deletion(-)
> >> >
> >> > diff --git a/libavformat/assenc.c b/libavformat/assenc.c
> >> > index d50f18feb1..9b44b16597 100644
> >> > --- a/libavformat/assenc.c
> >> > +++ b/libavformat/assenc.c
> >> > @@ -95,7 +95,9 @@ static void purge_dialogues(AVFormatContext *s, int
> >> force)
> >> >                    ass->expected_readorder, dialogue->readorder);
> >> >             ass->expected_readorder = dialogue->readorder;
> >> >         }
> >> > -        avio_printf(s->pb, "Dialogue: %s\r\n", dialogue->line);
> >> > +        avio_write(s->pb, "Dialogue: ", 10);
> >> > +        avio_write(s->pb, dialogue->line, strlen(dialogue->line));
> >> > +        avio_write(s->pb, "\r\n", 2);
> >>
> >> IMHO avio_printf should be fixed instead to use an AVBPrint buffer, this
> >> should remove the 4k limit from it.
> >>
> >
> > That is unrelated issue. Using avio_printf in this specific case is
> > overkill.
>
> Using 3 avio_writes instead is a useless micro optimalization which also
> reduces readblity, but feel free to apply if you feel stong about it.
>

I doubt so, make actual benchmark to prove your claims.
Allocation + memcpy is slower than direct writing.



>
> Regards,
> Marton
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