On Sun, 20 Sep 2020, Paul B Mahol wrote:
On Sat, Sep 19, 2020 at 11:46:50PM +0200, Marton Balint wrote:
On Sat, 19 Sep 2020, Paul B Mahol wrote:
> On Thu, Sep 17, 2020 at 12:31:06PM +0200, Paul B Mahol wrote:
> > This removes big CPU overhead for demuxing chained ogg streams.
> >
> > Signed-off-by: Paul B Mahol <one...@gmail.com>
> > ---
> > libavformat/aviobuf.c | 10 +++++-----
> > 1 file changed, 5 insertions(+), 5 deletions(-)
> >
>
> will apply soon.
Don't apply it, as I explained, it is not correct.
I carefully examined your explanation and I already reported
here on mailing list for every one to see that it does not work.
So please reconsider your blocking statement and provide
correct solution to problem.
Your solution will break the fundamentals of ffio_ensure_seekback, so it
is not OK. Checking if (buf_size <= s->buffer_size) will not guarantee
that the buffer will not be flushed when reading the next buf_size bytes
because buf_ptr can be anywhere in the buffer. See how fill_buffer()
works. It not only makes sure the buffer has space, it makes sure that the
buffer has max_buffer_size space available. If not, then it gets flushed.
There are some issues with current code, I will send a patch to fix them.
Unfortunately it will NOT fix your problem entirely. As I suggested, if
you use 2*max_buffer_size buffers by default, that might help you, but the
fundamental problem is that ffio_ensure_seekback simply cannot be
implemented efficiently with the current design. The guarantees should be
reduced (e.g. ffio_ensure_seekback can flush the buffer and invalidate
previous ffio_ensure_seekback request)
Regards,
Marton
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