question

kingargyle avatar image
kingargyle asked

Dolby Digtal Playback

I have a report from a user saying that their media files that contain an Dolby Digital audio track is playing back with out sound. I've checked the media specifications and it appears Dolby Digital is supposed to be supported in MP4 containers. I'm just using the standard android video player apis to play back the content. Is there a special api I need to use to get Dolby Digital content to play or is it limited to specific container formats.
fire tv
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Sujoy@Amazon avatar image
Sujoy@Amazon answered
I tried playing DolbyAudioExample.apk from below link on Fire TV http://developer.dolby.com/tools-tech.aspx It gave me below error "Dolby Audio Processing not available on this device." Though I can see below media type is supported in Fire TV eAC3 (Dolby Digital Plus) audio/eac3 Up to 48 kHz, 6 channels, 16-bit and 24-bit. MPEG-4 (.mp4, m4a) I need little assistance from you to demonstrate the issue to the team here. I am sending you a mail to your registered email id, please send me back at least one mp4 media that's dolby enabled and the player code (how you are playing it). You can put all this as a zip in a public storage and share me the path. Thanks.
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kingargyle avatar image
kingargyle answered
Thanks I've sent you a reply via email with the information you request.
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Sujoy@Amazon avatar image
Sujoy@Amazon answered
Hi Kingargyle, Thank you for the details through mail. I tried to play the .mkv media you using MediaPlayer API of Android in both the devices having Fire OS (Kindle HDX 8.9) and Android 4.4 (Nexus 7) and both the devices played the media without sound. But I see VLC player can play the mkv with dolby support. I am digging deep to understand the issue. Thanks.
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kingargyle avatar image
kingargyle answered
> Hi Kingargyle, > > Thank you for the details through mail. I tried to > play the .mkv media you using MediaPlayer API of > Android in both the devices having Fire OS (Kindle > HDX 8.9) and Android 4.4 (Nexus 7) and both the > devices played the media without sound. But I see VLC > player can play the mkv with dolby support. I am > digging deep to understand the issue. Thanks. I would expect the Android Nexus 7 not to play either audio track as the Nexus 7 doesn't have a Dolby Digital codec in the device. It only supports natively the AAC/MP3 audio formats for native playback of sound. VLC is able to play it because, it has it's own internal codec engine and player that it uses and doesn't use the native Android API or Media Controller. A Google TV device like a Sony GS7/GS8 device has native support with the base android API to playback and decode the Dolby Digital Sound tracks. It looks like for the Kindle Fire, one has to use the SDK you pointed to earlier. I would expect the Amazon Fire TV if it says it supports MP4 Dolby Digital to support this with out requiring a seperate SDK just as the Google TV device does. If this isn't the case, then I'm probably going to have to recommend users use an external player like VLC or other application with the app. Which in general won't provide a good user experience as compared to being able to use the built in Android native player. I suspect if you play back a file that is MP4 or MKV with an AAC sound track it'll play fine as the native player is handling those codecs when the file is requested to be played back. The Fire TV should be able to handle Dolby Digital in MP4 or MKV the same way if it says it supports it.
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Sujoy@Amazon avatar image
Sujoy@Amazon answered
Hi, Thanks for detail clarifications. Fire TV supports audio/eac3 codec which is in MPEG-4 (.mp4, m4a) container. This already said in below documentation https://developer.amazon.com/public/solutions/devices/fire-tv/docs/media-specifications Type-----------------------------Codec------------Mime Type--------------Details-------------------------Containers eAC3 (Dolby Digital Plus)------audio/eac3--------Up to 48 kHz------6 channels, 16-bit and 24-bit------MPEG-4 (.mp4, m4a) I played below mp4 media with MediaPlayer APIs in Fire TV and it played well all the channels in dolby mode http://download.dolby.com/Content_Download/channelcheck-large.mp4 This is the site contains several dolby media link that you provided in mail privately. Or documentation never said that it can support Dolby Digital for MKV format (Matroska container). So this is expected that you would not get native codec support for this format. Please write back if you need further clarification. Thanks.
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kingargyle avatar image
kingargyle answered
While it wasn't the answer I was hoping for, it does give me information to pass along to the users of my app. I would hope the team in charge of the video player will consider playing back Dolby Digital tracks or really any of the supported audio tracks regardless of the container format. I'll make sure I put up a wiki on this item as I'm sure I'm going to get more questions about it.
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Sujoy@Amazon avatar image
Sujoy@Amazon answered
We understand your point. Unfortunately, we cant generally answer questions about future products, services or enhancement, which this falls under. However, I'm going to forward this feedback/suggestion to the concern team. Please stay tuned on Mobile App Distribution Portal or Blogs ( https://developer.amazon.com/blog/index.html) for any updates related to this. Thanks.
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