low-latency video encoding creation failed, error code 12902

Question

Created Jul ’21

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VTCompressionSessionCreate returned 12902 if kVTVideoEncoderSpecification_EnableLowLatencyRateControl was picked. Code: CFMutableDictionaryRef encoderSpecification = CFDictionaryCreateMutable(kCFAllocatorDefault, 0, NULL, NULL);

CFDictionarySetValue(encoderSpecification, kVTVideoEncoderSpecification_EnableLowLatencyRateControl, kCFBooleanTrue);

OSStatus result = VTCompressionSessionCreate(kCFAllocatorDefault, 640, 360, kCMVideoCodecType_H264, encoderSpecification, nullptr, nullptr, cb, outputCallbackRefCon, &m_session);

if(result != noErr){ return result; }

Answer 1

xcvasd OP

Jul ’21

Got another message: Low latency RC mode requires hardware encoder. Here is my machine info: Hardware Overview:

Model Name: MacBook Pro

Model Identifier: MacBookPro17,1

Chip: Apple M1

Total Number of Cores: 8 (4 performance and 4 efficiency)

Memory: 8 GB

System Firmware Version: 6723.120.36

OS Loader Version: 6723.120.36

Serial Number (system): C02FK0FAQ05H

Hardware UUID: 098EBBDA-3841-5A29-B7C9-A982E675E6D5

Provisioning UDID: 00008103-000D446921D1001E

Activation Lock Status: Enabled

Answer 2

xcvasd OP

Jul ’21

Apple M1: Chipset Model: Apple M1 Type: GPU Bus: Built-In Total Number of Cores: 8 Vendor: Apple (0x106b) Metal Family: Supported, Metal GPUFamily Apple 7

So M1 chip doesn't support low latency RC mode? Can someone help? Thanks a lot in advance.

Answer 3

xcvasd OP

Jul ’21

modified the code little bit, and add RequireHardwareAcceleratedVideoEncoder in the encoder specification. const void *encoderKeys[] = { kVTVideoEncoderSpecification_RequireHardwareAcceleratedVideoEncoder,kVTVideoEncoderSpecification_EnableLowLatencyRateControl}, set both to true, but still get 12902 error.