Author Topic: Video/Audio output - 'Copy' and very slow saving of MP4 file  (Read 276 times)

ian666

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Video/Audio output - 'Copy' and very slow saving of MP4 file
« on: December 30, 2017, 05:22:09 PM »
Hi

Im using Avidemux 2.7.0 x64 from some time and i really like it for how easy it is to cut specific parts of MP4 file we dont want. This would be perfect peace of software if not rather slow saving of each file. Im not encoding anything, just loading MP4 file (x264 or x265 in MP4 container along with AAC audio), cutting out some stuff and saving it!.
There is no difference if im saving on same (1gbit) network drive location im reading (nas can read and write at 112MB/s over SMB), or if im saving file on my local nvme drive, Avidemux always does entire process very slow, reading file at around 25MB/s max which can result in like 500 frames per second and around 2 minutes of saving of 1.6GB file. Durning that time my cpu and graphics card sits on low clocks with 1-2% of usage. This looks like software problem since all other encoding programs can utiize my pc very well. Even Avidemux can use 100% of my cpu if i switch Video Output to for example Mpeg4 AVC (X264) but i want to save time and just save file without encoding.

My PC is Core i7 (6 core) 5820k with 32 gigs of 3200mhz quad channel ram, nvme drive Samsung 960Pro 1T and Gtx 1080Ti with Win10 Pro (newest drives and updates, but got this problem from day 1 of using avidemux which was half of year ago).

It would be great if someone could help me thanks!

Using thoose parameters:

Video Decoder: DXVA RGB (cannot really change it)
Video Output: Copy
Aidio Output (1 track): Copy

Output Format: MP4Muxer (using MP4v2 results in crash most of time)

Display tab got default settings:
Video Display: OpenGL (choosing DXVA2 will result in crash after loading video file, choosing Qt doesnt change anything)
Sdl driver: software (even if i change it, it stays on software)

Horizontal and Vertical deblocking checked, rest unchecked

HW Accel
Decode video using DXVA2 (windows) checked, cannot choose other ones since they are probably Linux exclusive.

CPU
Enable all SIMD checked

Random video media info:
Format                      : MPEG-4
Format profile              : Base Media
Codec ID                    : isom (isom/iso2/avc1/mp41)
File size                   : 1.65 GiB
Duration                    : 29 min 10 s
Overall bit rate            : 8 112 kb/s
Writing application         : Lavf57.56.101

Video
ID                          : 1
Format                      : AVC
Format/Info                 : Advanced Video Codec
Format profile              : Main@L4.1
Format settings             : CABAC / 2 Ref Frames
Format settings, CABAC      : Yes
Format settings, ReFrames   : 2 frames
Codec ID                    : avc1
Codec ID/Info               : Advanced Video Coding
Duration                    : 29 min 10 s
Bit rate                    : 7 976 kb/s
Width                       : 1 920 pixels
Height                      : 1 080 pixels
Display aspect ratio        : 16:9
Frame rate mode             : Variable
Frame rate                  : 29.970 (30000/1001) FPS
Minimum frame rate          : 29.970 FPS
Maximum frame rate          : 30.045 FPS
Color space                 : YUV
Chroma subsampling          : 4:2:0
Bit depth                   : 8 bits
Scan type                   : Progressive
Bits/(Pixel*Frame)          : 0.128
Stream size                 : 1.63 GiB (98%)

Audio
ID                          : 2
Format                      : AAC
Format/Info                 : Advanced Audio Codec
Format profile              : LC
Codec ID                    : mp4a-40-2
Duration                    : 29 min 10 s
Bit rate mode               : Constant
Bit rate                    : 128 kb/s
Channel(s)                  : 2 channels
Channel positions           : Front: L R
Sampling rate               : 48.0 kHz
Frame rate                  : 46.875 FPS (1024 SPF)
Compression mode            : Lossy
Stream size                 : 26.6 MiB (2%)
Default                     : Yes
Alternate group             : 1

P.s Happy New Year for everyone!
« Last Edit: December 30, 2017, 05:32:47 PM by ian666 »

Jan Gruuthuse

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Re: Video/Audio output - 'Copy' and very slow saving of MP4 file
« Reply #1 on: December 31, 2017, 05:39:05 AM »
Best performance you get is editing video on local hard disk and saving it there.
Then upload the saved video to NAS with filezilla or similar software.
Loading 12 GB from local hd = couple of minutes +-
Saving is similar duration +- 4300 to 5000 fps

In this example 1 Gb network transfer to N4100pro
Quote
18.9 (MB / s) = 151.2 Mb / s

Your network is the limiting factor, takes up to 12 minutes to transfer the file (FTP) to NAS.
Other hardware does not come in to play when using copy mode for both video & audio
« Last Edit: December 31, 2017, 06:51:11 AM by Jan Gruuthuse »

Jan Gruuthuse

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Re: Video/Audio output - 'Copy' and very slow saving of MP4 file
« Reply #2 on: December 31, 2017, 06:35:22 AM »
100 Mbps =  100/8 or   12.5 MB / sec speed file transfer (theoretical)
  1 Gbps = 1000/8 or  125   MB / sec speed file transfer (theoretical)


8 bit = 1 Byte
« Last Edit: December 31, 2017, 07:39:36 AM by Jan Gruuthuse »