4/15/2023 0 Comments Ubuntu ffmpeg unknow pcmThe meaning of the frame is vague in audio technology, as it means one thing in the case of AES3 and another thing in the case of Dolby E. During playback, if Dolby E decoding is not supported, the audio data may be misinterpreted as AES3 PCM data instead of AES3 NON-PCM data, which results in NOISE playback. Dolby E is represented as AES3 PCM, while in fact, it's AES3 NON-PCM. AES3 PCM of 2 channels - 48 kHz - (16, 20, 24) bits, has a bitrate of (1536, 1920, 2304) kbps, which is also the Dolby E bitrate in (16-bit, 20-bit, 24-bit) data mode. The Dolby E data mode defines the number of bits from each of the two AES3 subframes, that are utilized by the Dolby E stream/signal.ĭolby E in (16-bit, 20-bit, 24-bit) data mode is carried as AES3 PCM of 2 channels - 48 kHz - (16, 20, 24) bits, which means that (16, 20, 24) bits from each of the two AES3 subframes are utilized by Dolby E. Each subframe consists of 32 bits: 24 bits of maximum resolution (information) for each audio sample combined with 4 flag bits and 4 synchronization bits. An AES3 frame is divided into two subframes, one for each of the two channels. AES3 is made up of audio blocks, where each one of them contains 192 consecutive frames. An AES3 stream/signal can carry two channels of PCM audio data, up to 24 bits - 192 kHz. The bit depth of the Dolby E data mode is what is shown in MediaInfo.Ī Dolby E stream/signal is carried within an AES3 stream/signal in. The bit depth of the Dolby E data mode is carried as information in the metadata and doesn’t correlate to the bit depth of the Dolby E encoded audio. ![]() ![]() The 20-bit and 24-bit data modes with a maximum of 8 channels. ![]() The 16-bit data mode with a maximum of 6 channels. There are three data modes available for Dolby E, which are measured in bits and determine the number of channels that Dolby E can carry. The sample rate of the Dolby E encoded audio should always be at 48 kHz. It achieves an approximately 4:1 compression ratio and can withstand multiple encode-decode cycles without any audible degradation. Dolby E is a lossy audio codec introduced by Dolby Laboratories in 1999.
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