Update audio code to use size_t more correctly, webrtc/voice_engine/ portion.

Update audio code to use size_t more correctly, webrtc/voice_engine/ portion.

This is a piece of https://codereview.webrtc.org/1230503003 , split out to a
separate change to make reviewing easier.

BUG=chromium:81439
TEST=none

[Peter Kasting, 2015-07-10 19:52:42]

pkasting@chromium.org changed reviewers:
+ henrika@webrtc.org

[henrika_webrtc, 2015-07-13 07:38:08]

https://codereview.webrtc.org/1224163002/diff/20001/webrtc/voice_engine/chann...
File webrtc/voice_engine/channel.h (right):

https://codereview.webrtc.org/1224163002/diff/20001/webrtc/voice_engine/chann...
webrtc/voice_engine/channel.h:435: size_t number_of_frames,
It is not clear to me why size_t is required here. Can you provide some more
general background on why this sort of changes are done. I am sure that all is
OK; just want to understand and learn. Thanks.

[henrika_webrtc, 2015-07-13 08:03:21]

henrika@webrtc.org changed reviewers:
+ pbos@webrtc.org

[Peter Kasting, 2015-07-13 22:12:28]

https://codereview.webrtc.org/1224163002/diff/20001/webrtc/voice_engine/chann...
File webrtc/voice_engine/channel.h (right):

https://codereview.webrtc.org/1224163002/diff/20001/webrtc/voice_engine/chann...
webrtc/voice_engine/channel.h:435: size_t number_of_frames,
On 2015/07/13 at 07:38:08, henrika_webrtc wrote:
> It is not clear to me why size_t is required here. Can you provide some more
general background on why this sort of changes are done. I am sure that all is
OK; just want to understand and learn. Thanks.

Sure.  A fairly complete argument/set of tradeoffs can be found in the design
doc I wrote for a previous "use size_t more" change; see
https://docs.google.com/document/d/1I6nmE9D_BmCY-IoV6MDPY2V6WYpEI-dg2apWXTfZy...
.

If you want a short summary, basically the rule is "use size_t for object sizes
or lengths of containers in memory".  This matches how the STL works, is
approved by the Google style guide, promotes consistency of type usage, and can
sometimes simplify or clarify code by eliminating the possibility of certain
variables taking on negative values.

In this example, the actual frames are stored in memory, so we use a size_t to
count them.

[henrika_webrtc, 2015-07-14 07:54:01]

Nice work, thanks. LGTM.

May I ask how you find the places where to make these changes; any tool,
compiler warnings?

[henrika_webrtc, 2015-07-14 07:54:09]

https://codereview.webrtc.org/1224163002/diff/20001/webrtc/voice_engine/chann...
File webrtc/voice_engine/channel.cc (right):

https://codereview.webrtc.org/1224163002/diff/20001/webrtc/voice_engine/chann...
webrtc/voice_engine/channel.cc:3825: "Channel::MixAudioWithFile()
samples_per_channel_(%" PRIuS ") != "
Have not used this macro before. What does it expand to?

https://codereview.webrtc.org/1224163002/diff/20001/webrtc/voice_engine/chann...
File webrtc/voice_engine/channel.h (right):

https://codereview.webrtc.org/1224163002/diff/20001/webrtc/voice_engine/chann...
webrtc/voice_engine/channel.h:435: size_t number_of_frames,
Thanks!

[pbos-webrtc, 2015-07-14 08:07:59]

On 2015/07/14 07:54:09, henrika_webrtc wrote:
>
https://codereview.webrtc.org/1224163002/diff/20001/webrtc/voice_engine/chann...
> File webrtc/voice_engine/channel.cc (right):
> 
>
https://codereview.webrtc.org/1224163002/diff/20001/webrtc/voice_engine/chann...
> webrtc/voice_engine/channel.cc:3825: "Channel::MixAudioWithFile()
> samples_per_channel_(%" PRIuS ") != "
> Have not used this macro before. What does it expand to?

format string for printing size_ts, which is normally "zu" on posix systems.
This is name (PRIuS) non-standard but looks like PRId64 (print int64_t):

https://chromium.googlesource.com/external/webrtc/+/a03cd3fdef6c823e89c76bb09...

>
https://codereview.webrtc.org/1224163002/diff/20001/webrtc/voice_engine/chann...
> File webrtc/voice_engine/channel.h (right):
> 
>
https://codereview.webrtc.org/1224163002/diff/20001/webrtc/voice_engine/chann...
> webrtc/voice_engine/channel.h:435: size_t number_of_frames,
> Thanks!

[pbos-webrtc, 2015-07-14 08:15:10]

lgtm, but consider making channel counts size_t as well, since you multiply with
them to make another size_t.

https://codereview.webrtc.org/1224163002/diff/20001/webrtc/voice_engine/chann...
File webrtc/voice_engine/channel.cc (right):

https://codereview.webrtc.org/1224163002/diff/20001/webrtc/voice_engine/chann...
webrtc/voice_engine/channel.cc:3340: int number_of_channels) {
Make number_of_channels size_t as well?

https://codereview.webrtc.org/1224163002/diff/20001/webrtc/voice_engine/mock/...
File webrtc/voice_engine/mock/fake_voe_external_media.h (right):

https://codereview.webrtc.org/1224163002/diff/20001/webrtc/voice_engine/mock/...
webrtc/voice_engine/mock/fake_voe_external_media.h:46: int num_channels) {
num_channels size_t as well?

https://codereview.webrtc.org/1224163002/diff/20001/webrtc/voice_engine/utili...
File webrtc/voice_engine/utility.cc (right):

https://codereview.webrtc.org/1224163002/diff/20001/webrtc/voice_engine/utili...
webrtc/voice_engine/utility.cc:76: int num_channels,
size_t for num_channels?

[Peter Kasting, 2015-07-14 17:39:51]

On 2015/07/14 at 07:54:01, henrika wrote:
> Nice work, thanks. LGTM.
> 
> May I ask how you find the places where to make these changes; any tool,
compiler warnings?

THere's a disabled warning in MSVC for when a value is truncated by an implicit
cast, which gives me places to start looking for inconsistent type usage.  From
there it's just pulling the string of all transitive calls, as well as looking
at surrounding bits in the files I'm touching as I go.

[Peter Kasting, 2015-07-14 17:40:43]

On 2015/07/14 at 08:15:10, pbos wrote:
> lgtm, but consider making channel counts size_t as well, since you multiply
with them to make another size_t.

Yeah, I'm changing a lot of the channel counts to size_t, but that will probably
be done as a followon set of patches; I'll likely make a decision on whether to
try and lump those in today.

[Peter Kasting, 2015-07-17 00:13:47]

On 2015/07/14 at 17:40:43, Peter Kasting wrote:
> On 2015/07/14 at 08:15:10, pbos wrote:
> > lgtm, but consider making channel counts size_t as well, since you multiply
with them to make another size_t.
> 
> Yeah, I'm changing a lot of the channel counts to size_t, but that will
probably be done as a followon set of patches; I'll likely make a decision on
whether to try and lump those in today.

FYI, I'm going to do the channel counts change separately after this series of
patches lands, as it is indeed large: https://codereview.webrtc.org/1238083005

[pbos-webrtc, 2015-07-17 04:02:56]

On 2015/07/17 00:13:47, Peter Kasting wrote:
> On 2015/07/14 at 17:40:43, Peter Kasting wrote:
> > On 2015/07/14 at 08:15:10, pbos wrote:
> > > lgtm, but consider making channel counts size_t as well, since you
multiply
> with them to make another size_t.
> > 
> > Yeah, I'm changing a lot of the channel counts to size_t, but that will
> probably be done as a followon set of patches; I'll likely make a decision on
> whether to try and lump those in today.
> 
> FYI, I'm going to do the channel counts change separately after this series of
> patches lands, as it is indeed large: https://codereview.webrtc.org/1238083005

thanks! :)