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  1. I am very new at FFMPEG and just started learning.

    So I have an MXF file and I want to rewrap it to MOV, but do not touch audio and video settings. So the command I use is:
    ffmpeg -i input_file.mxf -acodec copy -vcodec copy -f mov output_file.mov
    However, even though audio in my input file is 2 channels stereo, FFMPEG gives me mono output. After the conversion, this information appears:
    Guessed Channel Layout for Input Stream #0.1 : mono
    Guessed Channel Layout for Input Stream #0.2 : mono
    My question is, what command should I use to force FFMPEG guesses Channel Layout as stereo?
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  2. Member
    Join Date
    Aug 2010
    Location
    San Francisco, California
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    You can try putting -ac 2 before the -i option. If that doesn't work, you can try adding -map_channel 0.1.0 -map_channel 0.2.0 somewhere before the output filename. BTW, your -f option is optional because FFmpeg will know you want MOV format from the filename extension.
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  3. Your source has 2 audio streams, which need to be merged to create stereo.
    amerge does the job, but it requires re-encoding the audio:
    Code:
    ffmpeg -y -hide_banner ^
    -i "video+2audiostreams.mxf" ^
    -filter_complex "[0:1:a][0:2:a]amerge" ^
    -channel_layout stereo ^
    -c:v copy -c:a aac -q:a 0.35 ^
    "video+stereo.mxf"
    Without re-encoding, it might be possible to flag the 2 streams as "L" and "R", but it won't be stereo.
    Last edited by raffriff42; 21st Feb 2017 at 02:25.
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  4. Member
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    Aug 2010
    Location
    San Francisco, California
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    Does it really have two streams or is FFmpeg misreading the file? OP tells us it is stereo. Perhaps a MediaInfo report would clarify.
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  5. Thank you for advices. I exported it from Premiere with only one audio track, so I have no idea why it would possibly have two streams. Here is MediaFile report:

    Format : MXF
    Commercial name : XDCAM HD422
    Format version : 1.2
    Format profile : OP-1a
    Format settings : Closed / Complete
    File size : 49,3 MiB
    Duration : 8s 40 ms
    Overall bit rate : 51,4 Mb/s
    Package name : Source Package
    Encoded date : 2017-02-20 14:41:52.928
    Writing application : Adobe Systems Incorporated Premiere Pro 1.0.0.0.1
    Writing library : win32 4.5.13.0.3

    Wideo
    ID : 512
    Format : MPEG Video
    Commercial name : XDCAM HD422
    Format version : Version 2
    Format profile : 4:2:2@High
    Format settings, BVOP : Tak
    Format settings, Matrix : Własny
    Format settings, GOP : Variable
    Format settings, picture structure : Frame
    Format settings, wrapping mode : Frame
    Codec ID : 0D01030102046001-0401020201040300
    Duration : 8s 40 ms
    Bit rate mode : Stała
    Bit rate : 50,0 Mb/s
    Width : 1.920 pikseli
    Height : 1.080 pikseli
    Display aspect ratio : 16:9
    Frame rate : 25,000 kl/s
    Standard : Component
    Color space : YUV
    Chroma subsampling : 4:2:2
    Bit depth : 8 bitów
    Scan type : Z przeplotem
    Scan order : Górne pole wpierw
    Bits/(Pixel*Frame) : 0.965
    Time code of first frame : 00:00:00:00
    Time code source : Group of pictures header
    Stream size : 47,9 MiB (97%)
    Color primaries : BT.709
    Transfer characteristics : BT.709

    Audio #1
    ID : 768
    Format : PCM
    Format settings, Endianness : Little
    Format settings, wrapping mode : Frame (AES)
    Codec ID : 0D01030102060300
    Duration : 8s 40 ms
    Bit rate mode : Stała
    Bit rate : 768 kb/s
    Channel(s) : 1 kanał
    Sampling rate : 48,0 kHz
    Frame rate : 25,000 kl/s (1920 spf)
    Bit depth : 16 bitów
    Stream size : 754 KiB (1%)
    Locked : Yes

    Audio #2
    ID : 1024
    Format : PCM
    Format settings, Endianness : Little
    Format settings, wrapping mode : Frame (AES)
    Codec ID : 0D01030102060300
    Duration : 8s 40 ms
    Bit rate mode : Stała
    Bit rate : 768 kb/s
    Channel(s) : 1 kanał
    Sampling rate : 48,0 kHz
    Frame rate : 25,000 kl/s (1920 spf)
    Bit depth : 16 bitów
    Stream size : 754 KiB (1%)
    Locked : Yes

    Other #1
    ID : 0-Material
    Type : Time code
    Format : MXF TC
    Time code of first frame : 00:00:00:00
    Time code settings : Material Package
    Time code, striped : Tak

    Other #2
    ID : 0-Source
    Type : Time code
    Format : MXF TC
    Time code of first frame : 00:00:00:00
    Time code settings : Source Package
    Time code, striped : Tak

    Other #3
    Type : Time code
    Format : SMPTE TC
    Muxing mode : SDTI
    Time code of first frame : 00:00:00:00
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  6. Marsia Mariner
    Guest
    The truth is, MXF is a weird & stupid container. Different from the good ones, it uses ONE audio channel per stream. Compared to the other containers, it does not know the meaning of «multichannel audio».
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