FFMPEG: can "select" audio channels using -acodec copy?

[marcorocchini]

Hi

please help me cat


I have this mxf file

https://www.dropbox.com/s/tveg47laoa1effa/C0044.MXF?dl=0

General
Complete name : C:\Users\Administrator\Dropbox\Public\C0044.MXF
Format : MXF
Commercial name : XDCAM HD422
Format profile : OP-1a
Format settings : Closed / Complete
File size : 79.0 MiB
Duration : 11s 0ms
Overall bit rate : 60.2 Mbps
Encoded date : 2014-06-21 19:40:29.000
Writing application : SONY Opt 1.22
Writing library : SONY Opt 1.22

Video
ID : 2
Format : MPEG Video
Commercial name : XDCAM HD422
Format version : Version 2
Format profile : 4:2:2@High
Format settings, BVOP : Yes
Format settings, Matrix : Custom
Format settings, GOP : M=3, N=12
Format settings, picture structure : Frame
Format settings, wrapping mode : Frame
Codec ID : 0D01030102046001-0401020201040300
Duration : 11s 0ms
Bit rate : 50.0 Mbps
Width : 1 920 pixels
Height : 1 080 pixels
Display aspect ratio : 16:9
Frame rate : 25.000 fps
Standard : Component
Color space : YUV
Chroma subsampling : 4:2:2
Bit depth : 8 bits
Scan type : Interlaced
Scan order : Top Field First
Compression mode : Lossy
Bits/(Pixel*Frame) : 0.965
Stream size : 65.6 MiB (83%)
Color primaries : BT.709
Transfer characteristics : BT.709
Matrix coefficients : BT.709

Audio #1
ID : 3
Format : PCM
Format settings, Endianness : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300
Duration : 11s 0ms
Bit rate mode : Constant
Bit rate : 1 152 Kbps
Channel(s) : 1 channel
Sampling rate : 48.0 KHz
Bit depth : 24 bits
Stream size : 1.51 MiB (2%)

Audio #2
ID : 4
Format : PCM
Format settings, Endianness : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300
Duration : 11s 0ms
Bit rate mode : Constant
Bit rate : 1 152 Kbps
Channel(s) : 1 channel
Sampling rate : 48.0 KHz
Bit depth : 24 bits
Stream size : 1.51 MiB (2%)

Audio #3
ID : 5
Format : PCM
Format settings, Endianness : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300
Duration : 11s 0ms
Bit rate mode : Constant
Bit rate : 1 152 Kbps
Channel(s) : 1 channel
Sampling rate : 48.0 KHz
Bit depth : 24 bits
Stream size : 1.51 MiB (2%)

Audio #4
ID : 6
Format : PCM
Format settings, Endianness : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300
Duration : 11s 0ms
Bit rate mode : Constant
Bit rate : 1 152 Kbps
Channel(s) : 1 channel
Sampling rate : 48.0 KHz
Bit depth : 24 bits
Stream size : 1.51 MiB (2%)

Audio #5
ID : 7
Format : PCM
Format settings, Endianness : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300
Duration : 11s 0ms
Bit rate mode : Constant
Bit rate : 1 152 Kbps
Channel(s) : 1 channel
Sampling rate : 48.0 KHz
Bit depth : 24 bits
Stream size : 1.51 MiB (2%)

Audio #6
ID : 8
Format : PCM
Format settings, Endianness : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300
Duration : 11s 0ms
Bit rate mode : Constant
Bit rate : 1 152 Kbps
Channel(s) : 1 channel
Sampling rate : 48.0 KHz
Bit depth : 24 bits
Stream size : 1.51 MiB (2%)

Audio #7
ID : 9
Format : PCM
Format settings, Endianness : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300
Duration : 11s 0ms
Bit rate mode : Constant
Bit rate : 1 152 Kbps
Channel(s) : 1 channel
Sampling rate : 48.0 KHz
Bit depth : 24 bits
Stream size : 1.51 MiB (2%)

Audio #8
ID : 10
Format : PCM
Format settings, Endianness : Little
Format settings, wrapping mode : Frame (AES)
Codec ID : 0D01030102060300
Duration : 11s 0ms
Bit rate mode : Constant
Bit rate : 1 152 Kbps
Channel(s) : 1 channel
Sampling rate : 48.0 KHz
Bit depth : 24 bits
Stream size : 1.51 MiB (2%)

Other #1
ID : 1-Material
Type : Time code
Format : MXF TC
Time code of first frame : 00:57:11:03
Time code settings : Material Package
Time code, striped : Yes

Other #2
ID : 1-Source
Type : Time code
Format : MXF TC
Time code of first frame : 00:57:11:03
Time code settings : Source Package
Time code, striped : Yes

Other #3
Type : Time code
Format : SMPTE TC
Muxing mode : SDTI
Time code of first frame : 00:57:11:03

that have several audio channel (or audio track?)

But now I would like generate a mxf file that have only the first and second audio channel (audio #1 and audio #2) that in the camera correspond to the CH1 audio channel, and CH2 audio channel. I don't want all the rest of audio channel

I would like generate a identical mxf with a "stereo" audio track L+R as the mxf-D10 SD (imx) files

I wonder can I do this with ffmpeg in -acodec copy mode so that audio quality is untouched?

ffmpeg -i c0044.mxf -vcodec copy -acodec copy -aspect 16:9 out.mxf

seems incorrect, how can I do? thanks

[poisondeathray]

use -map to select streams

ffmpeg -i C0044.MXF -map 0:0 -map 0:1 -map 0:2 -c:v copy -c:a copy -c:a copy output.mxf

Stream #0:0: Video: mpeg2video (4:2:2), yuv422p(tv, bt709), 1920x1080 [SAR 1
:1 DAR 16:9], 50000 kb/s, 25 fps, 25 tbr, 25 tbn, 50 tbc
Metadata:
file_package_umid: 0x060A2B340101010501010D4313000000B4041B0029680580 08004
602023B0270
Stream #0:1: Audio: pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s

Metadata:
file_package_umid: 0x060A2B340101010501010D4313000000B4041B0029680580 08004
602023B0270
Stream #0:2: Audio: pcm_s24le, 48000 Hz, 1 channels, s32 (24 bit), 1152 kb/s

.
.
.

0:0 is the video
0:1 is the 1st audio
0:2 is the 2nd audio
.
.
.


be careful - mediainfo stream numbering doesn't always correlate with ffmpeg numbering

[marcorocchini]

thank poison, I mean if is possible "merge" the 2 mono audio of audioCH1 and audioCH2 in one #ID,

keeping the -a:c copy for keeping the same quality

for example this is a mediainfo over a MXF IMX file, so that mediainfo says (for example):


Video
ID : 2
Format : MPEG Video
Commercial name : IMX 50
Format version : Version 2
Format profile : 4:2:2@Main
Format settings, BVOP : No
Format settings, Matrix : Default
Format settings, GOP : N=1
Format settings, picture structure : Frame
Format settings, wrapping mode : Frame (D-10)
Codec ID : 0D01030102010101-0401020201020101
Duration : 50s 680ms
Bit rate : 50.0 Mbps
Width : 720 pixels
Height : 576 pixels
Original height : 608 pixels
Display aspect ratio : 16:9
Frame rate : 25.000 fps
Standard : PAL
Color space : YUV
Chroma subsampling : 4:2:2
Bit depth : 8 bits
Scan type : Interlaced
Scan order : Top Field First
Compression mode : Lossy
Bits/(Pixel*Frame) : 4.823
Stream size : 304 MiB (80%)
Transfer characteristics : BT.470

Audio
ID : 3
Format : PCM
Format settings, Endianness : Little
Format settings, wrapping mode : Frame (D-10)
Codec ID : 0D01030102010101
Duration : 50s 680ms
Bit rate mode : Constant
Bit rate : 12.3 Mbps
Channel(s) : 4 channels
Channel(s)_Original : 8 channels
Channel positions : Front: L C R, Side: L R, Back: L R, LFE
Sampling rate : 48.0 KHz
Bit depth : 24 bits
Stream size : 74.2 MiB (20%)

because trying to use the amerge option I need the filter_complex that is not compatible with the -c:a copy option

I try to get the same audio (in blue color) of a mxf-imx file, in a mxf HD file, so that I have a "stereo" audio track

[ndjamena]

-acodec pcm_s24le

Unless you change the bitdepth or remix the channels conversion from one lossless format to another is always going to be lossless. It's debatable, yet irrelevant, whether converting PCM to PCM is any kind of conversion at all.

[poisondeathray]

I think you have to split it out into steps with a temporary wav currently with ffmpeg .

There is no way pick streams and map them using amerge or -map_channel or filter_complex to do what you want - to map it properly into the output video in 1 neat command currently

ffmpeg -i C0044.MXF -filter_complex "[0:1] [0:2] amerge" -c:a pcm_s24le -c:v copy output.wav
ffmpeg -i C0044.MXF -i output.wav -map 0:0 -map 1:0 -c:v copy -c:a copy output2.mxf 
del output.wav

[marcorocchini]

ahn, ok

and in this way the quality is the same? thanks

[poisondeathray]

Yes, quality is the same. Uncompressed 24bit PCM WAV to uncompressed 24bit PCM WAV . You can split out the channels to mono from the output and compare to the original if you want to be sure

[marcorocchini]

sorry poison, to avoiding the 2 commandlines is possible to use -af "pan=stereo:c0=c0:c1=c1" or -af "pan=stereo:c0<c0+c1:c1<c0+c1" or somethinf like this?

[poisondeathray]

Try it out. I couldn't get it to work

[marcorocchini]

hoewver if I don't mistake when I try to use the mkv container instead of mxf

ffmpeg -y -i C0044.MXF -filter_complex "[0:1] [0:2] amerge" -c:v copy -c:a pcm_s24le output56.mkv

it seems to encode ok... but is not a mxf

Hoewver, is possibile to encode in mkv but using the -af "pan=stereo:c0..."? thanks