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  1. #1
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    Am I crazy? Help streaming audio of m4a video files

    Hi,
    I recently setup LMS on an old Mac Mini. I wiped the Mac and installed El Capitan fresh, along with LMS.

    Everything is working fine except my Touch won't stream the audio for video files encoded with .m4a.

    Last year, on another Mac with LMS installed, the file's audio streamed fine via an SB3, I was archiving at the time, so I was considering converting the video to audio only but then didn't bother since the audio from the video file played fine.

    I've gone through all the 3rd party extensions and searched the forum for m4a, haven't seen the problem reported. Nor is m4a listed on the old wiki.

    Did I have something installed or set on the old machine that made this work? Is it an SB3/SBT difference?

    Or am I crazy?

    dmcdayton

  2. #2
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    TOuch can play M4a natively but they must be audio files.

    SB3 cannot play AAC files (which includes m4a) natively so it has tobe transcoded. Dependin on your setup the transcoder can be setuop just to play audio componernt of a file which has video and audio.

    Try disabling natively AAC (WebUI Settings/Advanced/File Types/ - not sure if AAC and/or MPEG-4 but try disbaling both) - this means playing files on Touch will also be transcoded just like Sb3.

  3. #3
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    Quote Originally Posted by bpa View Post
    Try disabling natively AAC (WebUI Settings/Advanced/File Types/ - not sure if AAC and/or MPEG-4 but try disbaling both) - this means playing files on Touch will also be transcoded just like Sb3.
    Much appreciated, I'd never have thought of "disabling" to "enable" but toggling the MPEG-4 to disable allows it to play.

    Also, turns out the file I was trying to play was audio only .m4a file, I had already exported the audio only out using QuickTime.

    Any idea why SBT won't just play that m4a file natively? Am I missing a library?

  4. #4
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    Quote Originally Posted by dmcdayton View Post
    Any idea why SBT won't just play that m4a file natively? Am I missing a library?
    MPEG4 is not a single format - it is a set of rules for a format inlcuding video, audio & optimisation for streaming. LMS streams the file to the player so some options for file based players will not work on Touch. Touch decoder only supports a very small number of the possible file format and so without looking at the actual file, it is pointless to suggest the specific problem area. The LMS decoder can handle a wider range of options.

  5. #5
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    Quote Originally Posted by bpa View Post
    MPEG4 is not a single format - it is a set of rules for a format inlcuding video, audio & optimisation for streaming. LMS streams the file to the player so some options for file based players will not work on Touch. Touch decoder only supports a very small number of the possible file format and so without looking at the actual file, it is pointless to suggest the specific problem area. The LMS decoder can handle a wider range of options.
    Thanks for the details. Is there somewhere in the LMS interface where it indicates in real time whether a particular file is being played back natively or transcoded? I poked around, couldn't see it. Can you suggest any reference material to educate myself on this as it relates to LMS?

    I have a rather large collection of audio extracted from various video formats, as well as more than a few Apple purchased audio files. It seems Apple uses m4a extension, for some reason I thought they used acc.

    I'd like to set so the Apple Music is natively decoded, then re-extract my video to proper audio format for native decoding to eliminate transcoding where possible..

  6. #6
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    Quote Originally Posted by dmcdayton View Post
    Can you suggest any reference material to educate myself on this as it relates to LMS?
    I found this site, any others recommended?
    http://wiki.slimdevices.com/index.php/Codec_comparison

  7. #7
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    Quote Originally Posted by dmcdayton View Post
    Thanks for the details. Is there somewhere in the LMS interface where it indicates in real time whether a particular file is being played back natively or transcoded? I poked around, couldn't see it. Can you suggest any reference material to educate myself on this as it relates to LMS?
    Not really - the best indication is More Info on the player under "Bitrate" you can see the message at the end "(converted to .."

    I have a rather large collection of audio extracted from various video formats, as well as more than a few Apple purchased audio files. It seems Apple uses m4a extension, for some reason I thought they used acc.
    This is where is starts to get techniocal. AAC is the audio encoding just like MP3. AAC and MP3 encoded audio is organised in frame and players needs to know where the frame begin - this is easy for file (there is a clear start) but not so easy when streaming as stream audio is a continuous of bytes. So audio encoding needs to be wrapped in a transport format - and this is MPEG4. MPEG4 is designed ot be general prupsoe and a MPEG4 files can hold video , audio incl multitrack, images, slideshows, subtitles etc.

    I'd like to set so the Apple Music is natively decoded, then re-extract my video to proper audio format for native decoding to eliminate transcoding where possible..
    Apple Music is not a format. It can be both lossy and lossless so already there are two choices.

    The best way to convert the file is to use ffmpeg where all the output format options can be carefully controlled. Conversion tools with GUI etc tend to make choices for a file based player which may not be the right ones for LMS streaming.

    The following command is a generic simple audio copy so it may not work with all files (e.g. mulittrack audio). The faststart flag is required for streaming. Not sure if it copies metadata.
    Code:
    ffmpeg -i input.m4a -vn -acodec copy -movflags +faststart output-audio.mp4
    How are you converting files now ?
    Last edited by bpa; 2019-03-21 at 09:59.

  8. #8
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    Quote Originally Posted by bpa View Post
    Apple Music is not a format. It can be both lossy and lossless so already there are two choices.

    How are you converting files now ?
    I was referring to music purchased from Apple, looks like their default is m4a file extension, CBR 16bit/44.1 kHz.

    I'd planned on using XLD and Quicktime.

    I've just noticed that all my mp3 extensions are disabled by default and greyed out in SBT...very odd. I haven't moved over my mp3 files yet.

    Do I need to install Lame for that to become enabled?

  9. #9
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    Quote Originally Posted by dmcdayton View Post
    I was referring to music purchased from Apple, looks like their default is m4a file extension, CBR 16bit/44.1 kHz.

    I'd planned on using XLD and Quicktime.

    I've just noticed that all my mp3 extensions are disabled by default and greyed out in SBT...very odd. I haven't moved over my mp3 files yet.

    Do I need to install Lame for that to become enabled?
    MP3 should only be greyed out if you disabled MP3 "native" - then you would need to install lame but why disable MP3 - it can only be audio and has no options which break decoding. ?

    XLD and quicktime likely to convert into a format for a file based player and not streaming players - so may not playable nativekly on Touch.

    m4a is apple extension for all sorts of quality variations but within their verison of a MPEG4 package. The file extension does not mean any specific quality or packaging options - just it is from Apple and to Apples preferences - ideally for apple ecosystem.

  10. #10
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    Quote Originally Posted by bpa View Post
    MP3 should only be greyed out if you disabled MP3 "native" - then you would need to install lame but why disable MP3 - it can only be audio and has no options which break decoding. ?

    XLD and quicktime likely to convert into a format for a file based player and not streaming players - so may not playable nativekly on Touch.

    m4a is apple extension for all sorts of quality variations but within their verison of a MPEG4 package. The file extension does not mean any specific quality or packaging options - just it is from Apple and to Apples preferences - ideally for apple ecosystem.
    I appreciate your help today, thanks!

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