How to cut video with ffmpeg with the same quality without reencoding

4th Dec 2014 02:05 #1

Member

Hello,
i am trying to cut a video with ffmpeg while keeping the same format and without reencoding the video.

The problem is that the format of the output is not the same.

The audio bitrate is less, the video bitrate is slightly changed and also the clip info has changed (this is only metadata right ?)

Also, the input file was a MP4, can ffmpeg keep the same format with all video formats ? Such as AVI, WMV, MOV, DIVX etc. ?

Thank you !

Command Line Arguments

Code:

ffmpeg.exe  -y -i "C:\Movies\304640436.mp4"  -ss 00:00:06.5 -t 8.40 "C:\Movies\304640436.clipped.mp4"

Mplayer Identify Output

Original

Code:

MPlayer2 git-6ce3c2a (C) 2000-2013 MPlayer2 Team
Custom build by Redxii, http://smplayer.sourceforge.net
Compiled against Libav version v9-553-g311443f
Build date: Fri Feb 22 16:43:48 EST 2013

Playing c:\movies\304640436.mp4.
Detected file format: QuickTime / MOV (libavformat)
ID_VIDEO_ID=0
[lavf] stream 0: video (h264), -vid 0
ID_AUDIO_ID=0
ID_AID_0_LANG=und
[lavf] stream 1: audio (aac), -aid 0, -alang und
[ass] No usable fontconfig configuration file found, using fallback.
Clip info:
 major_brand: mp42
ID_CLIP_INFO_NAME0=major_brand
ID_CLIP_INFO_VALUE0=mp42
 minor_version: 0
ID_CLIP_INFO_NAME1=minor_version
ID_CLIP_INFO_VALUE1=0
 compatible_brands: mp42mp41isomavc1
ID_CLIP_INFO_NAME2=compatible_brands
ID_CLIP_INFO_VALUE2=mp42mp41isomavc1
 creation_time: 2014-11-06 00:14:31
ID_CLIP_INFO_NAME3=creation_time
ID_CLIP_INFO_VALUE3=2014-11-06 00:14:31
ID_CLIP_INFO_N=4
Load subtitles in c:\movies\
ID_FILENAME=c:\movies\304640436.mp4
ID_DEMUXER=lavfpref
ID_VIDEO_FORMAT=H264
ID_VIDEO_BITRATE=4441456
ID_VIDEO_WIDTH=1920
ID_VIDEO_HEIGHT=1080
ID_VIDEO_FPS=25.000
ID_VIDEO_ASPECT=1.7778
ID_AUDIO_FORMAT=MP4A
ID_AUDIO_BITRATE=256000
ID_AUDIO_RATE=48000
ID_AUDIO_NCH=2
ID_START_TIME=0.00
ID_LENGTH=170.04
ID_SEEKABLE=1
ID_CHAPTERS=0
<vo_directx><ERROR>Your card doesn't support overlay
Opening video filter: [scale]
[ass] auto-open
Selected video codec: H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 [libavcodec]
ID_VIDEO_CODEC=ffh264
Selected audio codec: AAC (Advanced Audio Coding) [libavcodec]
AUDIO: 48000 Hz, 2 ch, floatle, 256.0 kbit/8.33% (ratio: 32000->384000)
ID_AUDIO_BITRATE=256000
ID_AUDIO_RATE=48000
ID_AUDIO_NCH=2
AO: [dsound] 48000Hz 2ch s16le (2 bytes per sample)
ID_AUDIO_CODEC=ffaac
Starting playback...
VIDEO:  1920x1080  25.000 fps  4441.5 kbps (555.2 kB/s)
ID_VIDEO_ASPECT=1.7778
[swscaler @ 02205d80]using unscaled yuv420p -> bgra special converter
VO: [directx] 1920x1080 => 1920x1080 BGRA 
No bind found for key '0x1b    '.

Exiting... (Quit)
ID_EXIT=QUIT

Clipped

Code:

MPlayer2 git-6ce3c2a (C) 2000-2013 MPlayer2 Team
Custom build by Redxii, http://smplayer.sourceforge.net
Compiled against Libav version v9-553-g311443f
Build date: Fri Feb 22 16:43:48 EST 2013

Playing c:\movies\304640436.clipped.mp4.
Detected file format: QuickTime / MOV (libavformat)
ID_VIDEO_ID=0
[lavf] stream 0: video (h264), -vid 0
ID_AUDIO_ID=0
ID_AID_0_LANG=und
[lavf] stream 1: audio (aac), -aid 0, -alang und
[ass] No usable fontconfig configuration file found, using fallback.
Clip info:
 major_brand: isom
ID_CLIP_INFO_NAME0=major_brand
ID_CLIP_INFO_VALUE0=isom
 minor_version: 512
ID_CLIP_INFO_NAME1=minor_version
ID_CLIP_INFO_VALUE1=512
 compatible_brands: isomiso2avc1mp41
ID_CLIP_INFO_NAME2=compatible_brands
ID_CLIP_INFO_VALUE2=isomiso2avc1mp41
 encoder: Lavf55.12.102
ID_CLIP_INFO_NAME3=encoder
ID_CLIP_INFO_VALUE3=Lavf55.12.102
ID_CLIP_INFO_N=4
Load subtitles in c:\movies\
ID_FILENAME=c:\movies\304640436.clipped.mp4
ID_DEMUXER=lavfpref
ID_VIDEO_FORMAT=H264
ID_VIDEO_BITRATE=4654776
ID_VIDEO_WIDTH=1920
ID_VIDEO_HEIGHT=1080
ID_VIDEO_FPS=25.000
ID_VIDEO_ASPECT=1.7778
ID_AUDIO_FORMAT=MP4A
ID_AUDIO_BITRATE=128536
ID_AUDIO_RATE=48000
ID_AUDIO_NCH=2
ID_START_TIME=-0.03
ID_LENGTH=8.43
ID_SEEKABLE=1
ID_CHAPTERS=0
<vo_directx><ERROR>Your card doesn't support overlay
Opening video filter: [scale]
[ass] auto-open
Selected video codec: H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 [libavcodec]
ID_VIDEO_CODEC=ffh264
Selected audio codec: AAC (Advanced Audio Coding) [libavcodec]
AUDIO: 48000 Hz, 2 ch, floatle, 128.5 kbit/4.18% (ratio: 16067->384000)
ID_AUDIO_BITRATE=128536
ID_AUDIO_RATE=48000
ID_AUDIO_NCH=2
AO: [dsound] 48000Hz 2ch s16le (2 bytes per sample)
ID_AUDIO_CODEC=ffaac
Starting playback...
VIDEO:  1920x1080  25.000 fps  4654.8 kbps (581.8 kB/s)
ID_VIDEO_ASPECT=1.7778
[swscaler @ 02205d80]using unscaled yuv420p -> bgra special converter
VO: [directx] 1920x1080 => 1920x1080 BGRA 
No bind found for key '0x1b    '.

Exiting... (Quit)
ID_EXIT=QUIT

Quote

4th Dec 2014 02:15 #2

Baldrick

I'm a MEGA Super Moderator

Add

Code:

-vcodec copy -acodec copy

To copy the video and audio stream.

Code:

ffmpeg.exe  -y -i "C:\Movies\304640436.mp4" -vcodec copy -acodec copy -ss 00:00:06.5 -t 8.40 "C:\Movies\304640436.clipped.mp4"

Quote

4th Dec 2014 10:50 #3

alexander121

Member

Thank you for your answer.

Do you also know how to accurately cut the video with ffmpeg while doing a bitstream copy ?

The ffmpeg site says :
Code:
Seeking while doing a bitstream copy

Using -ss as input option together with -c:v copy might not be accurate since ffmpeg is forced to only use/split on i-frames. Though it will—if possible—adjust the start time of the stream to a negative value to compensate for that.
I have found also this thread :
https://forum.videohelp.com/threads/359491-Just-an-idea-ffmpeg-based-key-frame-accurate-cutting

but did not understand their conclusion.

Thanks !

Quote

4th Dec 2014 10:53 #4

poisondeathray

Member

It's not possible to get frame accuracy in ffmpeg, unless the source video is intra encoded (I frame only)

You cannot cut in the middle of a GOP , because frames rely on data from other frames within a GOP

Quote

6th Dec 2014 01:51 #5

alexander121

Member

would it not be possible to write a program to find the most close I frame (or how else it is called - sorry i do not know the terminology)
and then pass in the -ss parameter the time of this frame as a value ?

Quote

6th Dec 2014 02:38 #6

hech54

Member

Originally Posted by alexander121

would it not be possible to write a program to find the most close I frame (or how else it is called - sorry i do not know the terminology)
and then pass in the -ss parameter the time of this frame as a value ?

Yes....you will find dozens of them in the TOOLS section....many of them are FREE. They show you exactly where you are cutting and they show/tell you if you can cut there losslessly. They are called Video Editors. AviDemux is my personal favorite.
I'll never understand the fascination with the frustration of Command Line devotees.....especially with simple video cuts.

Quote

8th Dec 2014 02:36 #7

Selur

Member

would it not be possible to write a program to find the most close I frame (or how else it is called - sorry i do not know the terminology)

That is what ffmpeg normally does automatically.
If the time doesn't hit a key frame the previous key frame will be used as starting point for the cut.

users currently on my ignore list: deadrats, Stears555

Quote

How to cut video with ffmpeg with the same quality without reencoding

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