PCM on TV, or Pulse-Code Modulation, refers to a digital audio encoding method. When selected as an audio output option on a TV, it typically means the TV will output audio in a basic, uncompressed digital format suitable for devices connected via HDMI. However, using PCM on your TV usually limits the audio output to 2.0 stereo sound.
Understanding PCM Audio
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Pulse-Code Modulation (PCM): A standard method used to digitally represent analog signals, like audio. It involves sampling the analog signal at regular intervals and then quantizing these samples into digital values.
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Uncompressed Audio: PCM is an uncompressed audio format, meaning the audio data is transmitted without any data reduction or compression algorithms applied. This preserves the audio quality but requires more bandwidth.
PCM in the Context of TV Audio Output
When you select PCM as the audio output option on your TV:
- Audio Source: The TV receives audio from various sources, such as broadcast TV, streaming apps, or devices connected via HDMI (e.g., Blu-ray player, game console).
- Audio Processing: The TV may perform minimal audio processing before outputting the signal as PCM.
- Output Format: The TV outputs the audio as uncompressed digital audio (PCM) through its available audio outputs, most commonly the HDMI ARC/eARC port or optical audio output.
- Channel Limitation: Often, when PCM is selected, the TV will only output a 2.0 stereo audio signal, meaning two channels (left and right). This is a limitation of many TVs and their PCM output capabilities. This means you won't get the full multi-channel surround sound experience (5.1, 7.1, etc.) that is available with other audio formats like Dolby Digital or DTS.
Why Use PCM?
- Compatibility: PCM is a widely supported audio format. Most audio devices, such as soundbars and AV receivers, can decode PCM audio.
- Simplicity: It is a straightforward, uncompressed format, which can sometimes be beneficial for devices that may struggle with more complex audio codecs.
- Pre-Processed Audio: As the reference states, PCM is ideal if the external device connected via HDMI has pre-processed the audio. For example, if a Blu-ray player has already decoded a Dolby TrueHD track and is outputting it as PCM, the TV simply passes through that pre-processed audio.
Limitations of PCM on TV
- Limited to 2.0 Stereo: The most significant drawback is the limitation to 2.0 stereo output on many TVs, preventing multi-channel surround sound.
- Lower Audio Quality Potential: While PCM is uncompressed, the limitation to stereo means you are missing out on the potential for higher fidelity and immersive audio offered by multi-channel surround sound formats.
Alternatives to PCM
If you want to enjoy multi-channel surround sound, consider these alternatives:
- Dolby Digital/Dolby Digital Plus: Compressed audio formats commonly used for broadcast TV and streaming.
- DTS: Another compressed audio format that supports multi-channel surround sound.
- Dolby TrueHD/DTS-HD Master Audio: Lossless, high-resolution audio formats typically found on Blu-ray discs. Use HDMI ARC/eARC to transmit these formats to your receiver if supported.
Conclusion
In summary, PCM on a TV refers to the use of Pulse-Code Modulation to output uncompressed digital audio. While simple and compatible, it often restricts the audio to 2.0 stereo, which may not be ideal for those seeking a full surround sound experience. Check your TV's manual to confirm if it supports multi-channel PCM output.
