AAC Stereo Playback Tests

HE-AAC v2 SBR Check and Channel ID

This tests for proper reproduction of the SBR portion of the HE-AAC bitstream and proper channel arrangement.

This bitstream contains:

SBR - 6, 8, 10, 12 kHz tones @ -16 dBFS, 0.5 seconds each. There is a 1 kHz -21 dBFS tone in both channels throughout.
- Left Channel
- Right Channel
EBU R49 Channel ID:
- 1 kHz -21 dBFS tone in both channels, left channel interrupted.
Spoken Channel Identification (English)
Narration: L+R Channels

AOT 5, explicit signalling, backwards compatible

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AOT 29, explicit signalling, backwards compatible

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AOT 29, explicit signalling, not backwards compatible (MPEG hierarchical)

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AOT 29, implicit signalling

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AOT 29, mixed signalling

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Original Wave File

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If the decoder supports SBR, all four tones, 6, 8, 10, and 12 KHz should be heard (or seen on a sound level meter if you have high-frequency hearing loss). If the decoder is only decoding the AAC-LC portion of the bitstream, only the first two tones will be heard. This is at the encoded bitrate of 56 kb/s, at other bitrates the SBR crossover frequency used by the encoder will vary, resulting in more or less tones being heard. Missing tones in only one channel may indicate a speaker problem.

In order to support legacy transport formats, several signalling techniques are presented here for HE-AAC v2. For MPEG-4 file format (ISO Base Media File Format) used with HTML 5 playback, explicit backwards compatible signalling is recommended as it offers the best compatibility with the widest range of players. More information on signalling is available in our AAC transport formats application bulletin listed on the Documents page of this site.

The MPEG-4 AAC audio bitstream is presented as an HTML5 audio object - which should play back correctly in:

Microsoft Internet Explorer 9+ (Win 7+ PC)
Google Chrome (Win 7+ PC, Mac OS, Android 4.4+)
Mozilla Firefox (Win 7+ PC, Mac OS)
Apple Safari (Mac OS, iOS)

Other combinations of browsers and platforms may work as well, an omission here does not mean it does not work.

The bitstream files, if downloaded locally, should also play correctly in:

Microsoft Windows Media Player 12 (Win 7+ PC)
Apple QuickTime (Mac OS))
VLC Player (Win 7+ PC) (except AOT 29, Non-backwards-compatible)

HE-AAC SBR Check and Channel ID - With H.264 Video

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This is the bitstream above (explicit backwards-compatible signalling) multiplexed with an explanatory graphic encoded in H.264 Main Profile at 400x400 resolution.

Troubleshooting

No sound or no rear channels? Check the troubleshooting page.