ARC vs eARC, PCM vs Bitstream — Getting Real Dolby Atmos
Complete guide to ARC vs eARC and PCM vs Bitstream for Dolby Atmos. Learn setup tips for getting lossless audio from your TV to soundbar or AVR.
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Technical Guide
Technical explanation
ARC vs eARC, PCM vs Bitstream — Getting Real Dolby Atmos 🔊🎬
🎯 Quick Summary
ARC (Audio Return Channel) and eARC (enhanced ARC) send audio from TV to soundbar/AVR. eARC has higher bandwidth for lossless Dolby Atmos. PCM sends uncompressed audio, while Bitstream sends compressed audio for external decoding. For best Atmos experience: use eARC with Bitstream mode.
📡 1. ARC vs eARC: The Bandwidth Battle
📻 ARC (Audio Return Channel)
🔧 Technical Specs
- • Bandwidth: ~1 Mbps
- • Max Channels: 5.1 surround
- • Supported Formats: DD, DD+
- • Lossless: Not supported
✅ What Works
- • Dolby Digital (5.1)
- • Dolby Digital Plus
- • Dolby Atmos via DD+ (compressed)
- • Basic lip-sync correction
🚀 eARC (Enhanced ARC)
🔧 Technical Specs
- • Bandwidth: ~37 Mbps
- • Max Channels: 7.1+ (object-based)
- • Supported Formats: All major formats
- • Lossless: Full support
✅ What Works
- • Dolby TrueHD (lossless)
- • DTS-HD Master Audio
- • Uncompressed Dolby Atmos
- • Automatic lip-sync correction
🎚️ 2. PCM vs Bitstream: Decoding Strategies
🔄 Understanding Audio Processing
📊 PCM (Pulse Code Modulation)
How It Works
- • TV/player decodes audio internally
- • Sends uncompressed channel data
- • Requires high bandwidth for multichannel
- • No metadata for object-based audio
Best For
- • Stereo content
- • Basic surround sound
- • When soundbar lacks advanced decoding
- • Simple setups
🎵 Bitstream
How It Works
- • TV/player sends compressed audio
- • Soundbar/AVR decodes externally
- • Preserves original audio format
- • Includes metadata for processing
Best For
- • Dolby Atmos content
- • DTS formats
- • Premium soundbars/AVRs
- • Maximum audio quality
📋 3. Audio Format Compatibility Matrix
🎛️ Format Support by Connection Type
| Audio Format | ARC | eARC | Notes |
|---|---|---|---|
| Dolby Digital (5.1) | ✅ | ✅ | Standard 5.1 surround |
| Dolby Digital Plus | ✅ | ✅ | Enhanced DD with higher bitrates |
| Dolby Atmos (DD+) | ⚠️ | ✅ | Compressed Atmos, limited channels |
| Dolby TrueHD | ❌ | ✅ | Lossless, requires eARC |
| Dolby Atmos (TrueHD) | ❌ | ✅ | Uncompressed Atmos, best quality |
| DTS-HD Master Audio | ❌ | ✅ | Lossless DTS, requires eARC |
| PCM 5.1 | ⚠️ | ✅ | May exceed ARC bandwidth |
| PCM 7.1 | ❌ | ✅ | Requires eARC bandwidth |
🔧 4. Setup Guide: Getting It Right
⚙️ Step-by-Step Configuration
1️⃣ Physical Connections
HDMI Cable Selection
Use certified Ultra High Speed HDMI 2.1 cables for eARC
TV Connection
Connect to TV's eARC port (usually HDMI 3 or 4)
Audio Device
Connect to soundbar/AVR's eARC port
2️⃣ TV Settings
Enable eARC
- • Sound Settings → eARC → On
- • HDMI CEC → Enable
- • Auto Power Sync → Enable
- • Digital Audio Out → Auto/Bitstream
Audio Passthrough
- • Audio Format → Bitstream
- • Dolby Atmos → Enable
- • DTS → Enable (if available)
- • Audio Delay → Auto
3️⃣ Streaming App Settings
Netflix
- • Audio → Original (5.1/Atmos)
- • Playback Settings → High
- • Dolby Atmos → Available on supported content
Disney+ Hotstar
- • Audio Language → English (5.1)
- • Quality → 4K (for Atmos)
- • Look for Dolby Atmos badge
🛠️ 5. Common Issues & Troubleshooting
❌ Audio Not Working
Symptoms
- • No sound from soundbar/AVR
- • Sound coming from TV speakers
- • Intermittent audio dropouts
- • Wrong audio format detected
Solutions
- • Check HDMI cable (try different cable)
- • Verify eARC is enabled on both devices
- • Power cycle all devices
- • Update firmware on TV and soundbar
⚠️ Limited Audio Quality
Symptoms
- • Only stereo sound on multichannel content
- • No Dolby Atmos despite capable hardware
- • Audio sounds compressed
- • Missing height/surround channels
Solutions
- • Switch TV audio to Bitstream mode
- • Enable Dolby Atmos in app settings
- • Check content actually has Atmos track
- • Verify soundbar supports the format
🔄 Lip Sync Issues
Symptoms
- • Audio ahead of video
- • Audio behind video
- • Sync varies by content/app
- • Worse with certain formats
Solutions
- • Enable Auto Lip Sync (eARC feature)
- • Adjust audio delay in soundbar/AVR
- • Use Bitstream instead of PCM
- • Update device firmware
🇮🇳 6. Indian Market: Device Compatibility
📱 Popular Devices & eARC Support
📺 Smart TVs
Premium Models
Samsung QLED, LG OLED, Sony Bravia (2019+)
Mid-Range
OnePlus TV, Mi TV (select models)
Budget
Most budget TVs: ARC only
🔊 Audio Systems
Premium Soundbars
Samsung Q-series, LG SN series, Sony HT-Z9F
AVR Systems
Denon, Marantz, Yamaha (2019+ models)
Budget Options
Boat, boAt, JBL (basic ARC support)
📺 7. OTT Platform Audio Support
🎬 Streaming Services Audio Quality
Netflix India
- • Dolby Atmos on premium plan
- • 5.1 surround on select content
- • Requires compatible device
- • Look for Dolby Vision + Atmos badge
Amazon Prime Video
- • Dolby Atmos on select originals
- • 5.1 surround widely available
- • Best quality on Fire TV devices
- • Audio settings in playback menu
Disney+ Hotstar
- • Dolby Atmos on Marvel/Star Wars
- • Premium subscription required
- • Limited to 4K content
- • English audio tracks preferred
YouTube
- • 5.1 surround on select videos
- • No Dolby Atmos support
- • Quality depends on upload
- • Best on YouTube TV app
🛒 8. Buying Guide: What to Look For
✅ Essential Features
❌ Avoid These Issues
🚀 9. Future of Audio Standards
🔮 What's Coming Next
HDMI 2.1a: Enhanced eARC with better bandwidth management
Dolby Atmos Music: Spatial audio for streaming music services
DTS:X Pro: Enhanced object-based surround sound
Wireless eARC: Eliminating cable connections for audio
AI Audio Processing: Smart format detection and optimization
❓ 10. FAQ: ARC, eARC & Dolby Atmos
Q: Do I need eARC for Dolby Atmos?
A: Not always. ARC can handle compressed Atmos via Dolby Digital Plus, but eARC is required for lossless Atmos via Dolby TrueHD with maximum quality and channel count.
Q: Should I use PCM or Bitstream for Atmos?
A: Use Bitstream for Dolby Atmos. PCM strips the Atmos metadata and only sends channel-based audio, losing the object-based positioning information.
Q: Why does my soundbar show "PCM" instead of "Dolby Atmos"?
A: Your TV is likely decoding the audio instead of passing it through. Change TV audio settings to "Bitstream" or "Auto" to preserve the original format.
Q: Can I use regular HDMI cables for eARC?
A: For basic eARC, high-speed HDMI cables work. For best reliability and future compatibility, use certified Ultra High Speed HDMI cables.
Q: Why is there a delay between video and audio?
A: Audio processing in the soundbar/AVR causes delay. Use the Auto Lip Sync feature in eARC, or manually adjust audio delay settings.
📋 11. Summary & Key Takeaways
🎯 Essential Points
Connection Priority
- • eARC > ARC for audio quality
- • Bitstream > PCM for Atmos content
- • Use certified HDMI cables
- • Enable passthrough on TV
Setup Success
- • Check both devices support eARC
- • Configure TV and soundbar settings
- • Verify streaming app audio settings
- • Test with known Atmos content
🎯 Key Takeaways
This article explains the key concepts behind HDMI Audio Standards in simple terms for TVs & Audio Systems buyers.