Audio

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Audio output

HMP and DiVA players are capable of outputting two-channel audio (i.e. stereo) as:

Simultaneous audio via both HDMI (digital) and 3.5 jack (analogue) is supported only on HMP200, HMP130, and HMP100 devices; nevertheless we do not recommend using both outputs in the same environment as there might be phase / sync issues depending on the screen or HDMI decoder.


Note Notes:
  • The analog audio output is suitable to drive professional audio equipment (+4dBu pro line level) with a margin of 4.66 dB or consumer equipment (-10 dBV consumer level).
  • HDCP content via the HDMI port is not supported; HDCP protected content will not be played.
  • Audio decoding and audio output require some of the CPU power, therefore enabling the audio on the player might have an influence on the overall rendering quality of the content.

Enable audio output

The audio output is disabled by default on the HMP, it can be enabled by activating the "Enable audio output" check-box option from Control Center:

Audio decoding

Note
Because video and audio are often used together, more details on this topic are available under Video decoding page.

File formats

The following container formats are supported for files with audio:

Extension Description Audio codecs Notes
.mp3 Raw MPEG audio elementary stream MPEG Audio Layer III
.ac3 Raw AC-3 elementary stream AC-3 Not supported on HMP200, HMP130, and HMP100.
.wma Raw WMA elementary stream WMA2
.m4a, .mp4 MPEG-4 Part 14 Audio Only AAC
.mka Matroska Audio Only AAC Not supported on HMP200, HMP130, and HMP100.
.wav RIFF Audio File Format PCM, DTS
.aiff, .aif Audio Interchange File Format PCM Supported only on HMP200, HMP130 and HMP100.


Note Note:
Audio files are not supported and cannot be uploaded as Fusion content.

Codecs

Supported audio codecs

  • AAC
    Advanced Audio Coding (AAC) is an audio coding standard for lossy digital audio compression. Designed to be the successor of the MP3 format, AAC generally achieves better sound quality than MP3 at similar bit rates.AAC has been standardized by ISO and IEC, as part of the MPEG-2 and MPEG-4 specifications. High Efficiency Advanced Audio Coding (HE-AAC) which is part of MPEG-4 Audio is an extension of Low Complexity AAC (AAC LC).
    Supported profiles (up to 6 channels input): (MPEG-2 Part 7) Low Complexity Profile, (MPEG-4 Part 3) AAC Profile and High-Efficiency AAC Profile (note that HE-AAC v2 profile is supported only on DiVA, HMP350 and HMP300; up to 8 channels input).
  • MPEG-1/2 Layer III (MP3)
    MPEG-1 or MPEG-2 Audio Layer III, more commonly referred to as MP3, is an audio coding format for digital audio which uses a form of lossy data compression. Supported: 48KHz max sample rate and 2 channels. The previous versions: MPEG-1/2 Audio Layer II (MP2) and MPEG-1 Audio Layer I (MP1) are supported as well;
  • Windows Media Audio (WMA v2).
    WMA is a lossy audio codec which can encode audio signals sampled at up to 48 kHz with up to two discrete channels (stereo). Like AAC, WMA was intended to address perceived deficiencies in the MP3 standard.
  • Linear PCM (LPCM);
    Linear pulse-code modulation (LPCM) is a specific type of PCM where the quantization levels are linearly uniform. Supported only on HMP200, HMP130 and HMP100.
  • ITU-T G.711 and G.726;
    G.711 is an ITU-T standard for audio companding. It is primarily used in telephony. G.726 is an ITU-T ADPCM speech codec standard covering the transmission of voice. Supported only on HMP200, HMP130 and HMP100.
  • AC3 (Dolby Digital)
    Dolby Digital is the name for audio compression technologies, developed by Dolby Laboratories, containing up to six discrete channels of sound. AC-3 supports audio sample-rates up to 48 kHz. Supported on DiVA, HMP350 and HMP300 players.

Unsupported audio codecs

This list is not exhaustive and any codec that is not written above, should be considered as part of this list.

  • 24-bit PCM audio;
  • MPEG-4 SLS (HD-AAC);
  • Raw AAC files (use AAC within an MP4 or M4A file instead!);
  • RealAudio.

Audio content in Fusion

Note
This section applies only to HMP200, HMP130, and HMP100 devices.

Audio files cannot be directly uploaded as Fusion content, however it is possible to use audio content within Fusion.

The solution is to upload the audio files via a Style Pack or pulled them into the "publish" folder through Pull Mode, and then include the audio content into a Fusion Skin or a Fusion Template.

Audio level control

Using Elementi

Advanced Properties

It is possible to control the audio level of a media content in Elementi, using the "audio-level" property of the media layer. For that, follow these steps:

  1. Open the Layer Properties dialog, Advanced tab.
  2. Click on the "Click to add..." field under the "Name" column until the selection box is expanded.
  3. Select the "audio-level" property from the list.
  4. Click on the right column next to it (under the "Value" column).
  5. Enter a numeric value between 0 (no audio) and 1 (maximum level).
  6. Press the "Enter" key to validate the chosen value.
  7. Click on the "OK" button to save the changes.

Advanced

For advanced users, the audio level can be changed through jSignage (via the audioLevel attribute) or directly within the SVG code (via the audio-level property). The audio level can be set on:

  • the animation / audio / video elements individually,
  • on the entire document using a <set> element. (Note that the audio-level attribute doesn't have any effect when used directly on the <svg> element).

Example of SVG code:

<svg xmlns="http://www.w3.org/2000/svg" [...] >
  <set attributeName="audio-level" to="0.7"/> 
  ...
  <video audio-level="0.5" height="360" width="640" xlink:href="my_video.avi" id="my_video">
  ...
</svg>

Example of jSignage code (using the attr function):

$('#my_video').attr( 'audio-level', 0 ); // mute the audio

Troubleshooting

  • When using audio and interactivity make sure that the Reduce latency to 60ms when events are received option is NOT enabled.
  • Using audio in the background, while rendering a complex project may need special optimizations during content creation, otherwise the audio may shutter.
    For this, you need to identify the content that is "heavy" to render by the player (see the player logs) and optimize it (if possible) or remove it.
  • In some cases, the audio may play only for few seconds and then stay silent.
    This is the result of a non-optimal multiplexing of the audio and video streams that requires more than 1 MB of buffering of the audio or video stream in order to keep it in sync with the other. In this case the player.log has the following error:
    Stream demuxing failed because more than 1048576 bytes of buffering is required
    Re-encoding the media, either within Elementi 2015 (or later) or with another application (like FFMpeg) should fix the image freeze or the audio lost. Alternatively, the spx:maxDemuxingBufferSize attribute could be increased.
  • Skipping granule errors for MP3 files
    The resources.log might show decoding errors at INFO level for MP3 files. This error (skipping granule) is harmless and can usually be ignored. Constant bit rate MP3s can use a Bit Reservoir which can save redundant bits in a frame for the next frame, if they are not all used (i.e. if the content is not that complex). Part of the next frame is then decoded in advance. If the file has been edited in the middle of two frames which use this, then the granule is discarded. It should normally have next to no audible difference, as each granule represents a few milliseconds of the file.
This page was last modified on 9 February 2017, at 11:52.