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iOS HW encoder: Increase data rate limit

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The iOS H264 video toolbox encoder is currently undershooting the
intended bitrate. This seems to be caused by the data rate limit
property. This CL increases the data rate limit to a set
percentage above the intended bitrate to avoid undershooting. The
AverageBitRate property is still set to the intended bitrate, which
keeps it from overshooting the intended bitrate.

BUG=b/28713684

Review-Url: https://codereview.webrtc.org/2177873003
Cr-Commit-Position: refs/heads/master@{#13526}
This commit is contained in:
magjed
2016-07-26 03:10:33 -07:00
committed by Commit bot
parent d9c7f8d3a8
commit 62d695f655
1 changed files with 8 additions and 2 deletions
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10
webrtc/modules/video_coding/codecs/h264/h264_video_toolbox_encoder.cc
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@ -28,6 +28,11 @@
namespace internal {
// The ratio between kVTCompressionPropertyKey_DataRateLimits and
// kVTCompressionPropertyKey_AverageBitRate. The data rate limit is set higher
// than the average bit rate to avoid undershooting the target.
const float kLimitToAverageBitRateFactor = 1.5f;
// Convenience function for creating a dictionary.
inline CFDictionaryRef CreateCFDictionary(CFTypeRef* keys,
CFTypeRef* values,
@ -519,11 +524,12 @@ void H264VideoToolboxEncoder::SetEncoderBitrateBps(uint32_t bitrate_bps) {
bitrate_bps);
// TODO(tkchin): Add a helper method to set array value.
int64_t bytes_per_second_value = bitrate_bps / 8;
int64_t data_limit_bytes_per_second_value = static_cast<int64_t>(
bitrate_bps * internal::kLimitToAverageBitRateFactor / 8);
CFNumberRef bytes_per_second =
CFNumberCreate(kCFAllocatorDefault,
kCFNumberSInt64Type,
&bytes_per_second_value);
&data_limit_bytes_per_second_value);
int64_t one_second_value = 1;
CFNumberRef one_second =
CFNumberCreate(kCFAllocatorDefault,