[FFmpeg-devel] [PATCHv2 5/6] avformat/mpegtsenc: fix PCR generation intervals

[Andreas Håkon]

Hi Marton,


> > This new version LGTM.

> Thanks. I did a slight change for VBR streams and tried to mimic the old
> behaviour when selecting a PCR interval. Will post an updated version, but
> that should only affect VBR.

Regarding this new VBR patch I have one comment...


‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Saturday, 10 de August de 2019 22:27, Marton Balint <cus at passwd.hu> wrote:

> PCR generation was based on counting packets for both CBR and VBR streams.
> Couting packets might have worked for CBR streams (when muxrate was specified)
> but it only took into account the packets of a service (or the packets of the
> PCR stream lately), so even that was problematic for multi program streams.
>
> The new code works on actual timestamps for both CBR and VBR streams. For VBR
> streams the behaviour of the old code is simulated by selecting a PCR interval
> which is the highest multiple of the frame duration but still less than 100 ms.
>
> It should be trivial to add support for setting the PCR interval for VBR
> streams as well in a later patch.
>
> The accuracy of PCR packets for CBR streams was greatly improved by preemtively
> sending them at PCR intervals even if sending the payload of another stream
> is in progress.
>
> Signed-off-by: Marton Balint cus at passwd.hu
>
> libavformat/mpegtsenc.c | 90 +++++++++++++++++++++++++++++--------------------
> 1 file changed, 54 insertions(+), 36 deletions(-)
>
> diff --git a/libavformat/mpegtsenc.c b/libavformat/mpegtsenc.c

> [...]

> +          /* For VBR we select the highest multiple of frame duration which is less than 100 ms. */

Don't you think it's a good idea to use the parameter "pcr_period" as the limit,
instead of a fixed value of 100ms?

> [...]


And I think you've forgotten the file "muxers.texi" in this v2 version of the patch.
(the original patch 5 has it).

Regards.
A.H.

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