On Tue, 28 Apr 2020, Fu, Linjie wrote:
From: Martin Storsjö <mar...@martin.st>
Sent: Tuesday, April 28, 2020 03:28
static const AVCodecDefault svc_enc_defaults[] = {
+ { "b", "0" },
+ { "g", "120" },
{ "qmin", "-1" },
Why do you hardcode a value for g here, but put the default bitrate value
in the code above? Wouldn't it be clearer to have both defaults here at
the same place?
A default value in svc_enc_defaults[] would help to distinguish between
"the user specified the bitrate to be <x>" vs. "the user did not specify
anything
about the target bitrate", as Anton has suggested in [1].
Considering about your suggestions in patch 1/9, IMO it seems to be more
reasonable
to keep the uiIntraPeriod untouched. The libopenh264 library would fill the
default
value of uiIntraPeriod to 0, and as a consequence the gop size would be rather
large.
Updated the default "g" to "-1", same as libx264 did.
(Note that it's not acceptable for bitrate, since bitrate = 0 as default in
library is not
valid)
If we have the option of not setting the bitrate on the encoder, then yes,
it's better to avoid setting one in svc_enc_defaults. But in this case, if
no bitrate was chosen by the user, we end up enforcing a default value
anyway - just that the default is not written in the global defaults table
(libavcodec/options_table.h) and not in svc_enc_defaults, but instead in
code.
If we actually need to set a bitrate, it's IMO better to put this default
in the table, especially if we have other defaults like gop size there.
// Martin
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