[FFmpeg-devel] [PATCH v2] avformat/movenc : Don't write sidx for empty urls

[Michael Niedermayer]

On Fri, Nov 30, 2018 at 05:52:35AM +0000, Jeyapal, Karthick wrote:
> 
> On 11/29/18 11:08 PM, Michael Niedermayer wrote:
> > On Wed, Nov 28, 2018 at 09:45:24PM +0530, Karthick J wrote:
> >> When movenc is used by other segmenting muxers such as dashenc, url field is always empty.
> >> In such cases it is better to not write sidx, instead of throwing errors.
> >> ---
> >>  libavformat/movenc.c | 3 +++
> >>  1 file changed, 3 insertions(+)
> >
> > please correct me if i misunderstand but
> > dashenc enables global sidx, skiping writing the sidx then always seems a bit
> > odd
> Your understanding is correct. 
> But the motive of dashenc is to disable writing of sidx atom for every moof atom (Let's call this as local sidx for the sake of discussion).
> We wanted to disable local sidx as it was adding significant bitrate overhead for chunked streaming(where each frame is a moof).
> To disable local sidx we enabled global sidx. And global sidx was not writing any sidx at all from dashenc due to lack of url. 
> This behavior of not writing any sidx at all is also acceptable for dash. But we just wanted to remove the error, and hence this patch.
> Maybe one could add a new option no_sidx in movenc for this functionality. But since global_sidx was already achieving the same functionality new option seemed a bit redundant.

I have no real oppinion on how to solve it, adding a more specific option
could be done.
but enabling global_sidx and then not doing it silently seems quite hackish
as the intended behavior.
I mean please implement this cleanly, whichever way makes most sense.

thanks

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Observe your enemies, for they first find out your faults. -- Antisthenes
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