ffmpeg is writing that information to stderr, not stdout. Try this:

ffmpeg -i file.mp4 2>&1 | grep Duration | sed 's/Duration: \(.*\), start/\1/g'

Notice the redirection of stderr to stdout: 2>&1

EDIT:

Your sed statement isn't working either. Try this:

ffmpeg -i file.mp4 2>&1 | grep Duration | awk '{print $2}' | tr -d ,

You could try this:

/*
* Determine video duration with ffmpeg
* ffmpeg should be installed on your server.
*/
function mbmGetFLVDuration($file){


//$time = 00:00:00.000 format
$time =  exec("ffmpeg -i ".$file." 2>&1 | grep 'Duration' | cut -d ' ' -f 4 | sed s/,//");


$duration = explode(":",$time);
$duration_in_seconds = $duration[0]*3600 + $duration[1]*60+ round($duration[2]);


return $duration_in_seconds;


}


$duration = mbmGetFLVDuration('/home/username/webdir/video/file.mov');
echo $duration;

In case of one request parameter it is simplier to use mediainfo and its output formatting like this (for duration; answer in milliseconds)

mediainfo --Output="General;%Duration%" ~/work/files/testfiles/+h263_aac.avi

outputs

24840

For those who want to perform the same calculations with no additional software in Windows, here is the script for command line script:

set input=video.ts


ffmpeg -i "%input%" 2> output.tmp


rem search "  Duration: HH:MM:SS.mm, start: NNNN.NNNN, bitrate: xxxx kb/s"
for /F "tokens=1,2,3,4,5,6 delims=:., " %%i in (output.tmp) do (
if "%%i"=="Duration" call :calcLength %%j %%k %%l %%m
)
goto :EOF


:calcLength
set /A s=%3
set /A s=s+%2*60
set /A s=s+%1*60*60
set /A VIDEO_LENGTH_S = s
set /A VIDEO_LENGTH_MS = s*1000 + %4
echo Video duration %1:%2:%3.%4 = %VIDEO_LENGTH_MS%ms = %VIDEO_LENGTH_S%s

Same answer posted here: How to crop last N seconds from a TS video

You can use ffprobe:

ffprobe -i <file> -show_entries format=duration -v quiet -of csv="p=0"

It will output the duration in seconds, such as:

154.12

Adding the -sexagesimal option will output duration as hours:minutes:seconds.microseconds:

00:02:34.12

From my experience many tools offer the desired data in some kind of a table/ordered structure and also offer parameters to gather specific parts of that data. This applies to e.g. smartctl, nvidia-smi and ffmpeg/ffprobe, too. Simply speaking - often there's no need to pipe data around or to open subshells for such a task.

As a consequence I'd use the right tool for the job - in that case ffprobe would return the raw duration value in seconds, afterwards one could create the desired time format on his own:

$ ffmpeg --version
ffmpeg version 2.2.3 ...

The command may vary dependent on the version you are using.

#!/usr/bin/env bash
input_file="/path/to/media/file"


# Get raw duration value
ffprobe -v quiet -print_format compact=print_section=0:nokey=1:escape=csv -show_entries format=duration "$input_file"

An explanation:

"-v quiet": Don't output anything else but the desired raw data value

"-print_format": Use a certain format to print out the data

"compact=": Use a compact output format

"print_section=0": Do not print the section name

":nokey=1": do not print the key of the key:value pair

":escape=csv": escape the value

"-show_entries format=duration": Get entries of a field named duration inside a section named format

Reference: ffprobe man pages

ffmpeg has been substituted by avconv: just substitute avconb to Louis Marascio's answer.

avconv -i file.mp4 2>&1 | grep Duration | sed 's/Duration: \(.*\), start.*/\1/g'

Note: the aditional .* after start to get the time alone !!

I would just do this in C++ with a text file and extract the tokens. Why? I am not a linux terminal expert like the others.

To set it up I would do this in Linux

ffmpeg -i <file> 2>&1 | grep "" > mytext.txt

and then run some C++ app to get the data needed. Maybe extract all the important values and reformat it for further processing by using tokens. I will just have to work on my own solution and people will just make fun of me because I am a Linux newbie and I do not like scripting too much.

Argh. Forget that. It looks like I have to get the cobwebs out of my C and C++ programming and use that instead. I do not know all the shell tricks to get it to work.

This is how far I got.

ffmpeg -i myfile 2>&1 | grep "" > textdump.txt

and then I would probably extract the duration with a C++ app instead by extracting tokens.

I am not posting the solution because I am not a nice person right now

Update - I have my approach to getting that duration time stamp

Step 1 - Get the media information on to a text file

ffprobe -i myfile 2>&1 | grep "" > textdump.txt

OR

ffprobe -i myfile 2>&1 | awk '{ print }' > textdump.txt

Step 2 - Home in on the information needed and extract it

cat textdump.txt |  grep "Duration" | awk '{ print $2 }' | ./a.out

Notice the a.out. That is my C code to chop off the resulting comma because the output is something like 00:00:01.331,

Here is the C code that takes stdin and outputs the correct information needed. I had to take the greater and less than signs out for viewing.

#include stdio.h
#include string.h
void main()
{
//by Admiral Smith Nov 3. 2016
char time[80];
int len;
char *correct;
scanf("%s", &time);
correct = (char *)malloc(strlen(time));
if (!correct)
{
printf("\nmemory error");
return;
}
memcpy(correct,&time,strlen(time)-1);
correct[strlen(time)]='/0';
printf("%s", correct);
free(correct);
}

Now the output formats correctly like 00:00:01.33

ffmpeg -i abc.mp4 2>&1 | grep Duration | cut -d ' ' -f 4 | sed s/,//

gives output

HH:MM:SS.milisecs

I recommend using json format, it's easier for parsing

ffprobe -i your-input-file.mp4 -v quiet -print_format json -show_format -show_streams -hide_banner


{
"streams": [
{
"index": 0,
"codec_name": "aac",
"codec_long_name": "AAC (Advanced Audio Coding)",
"profile": "HE-AACv2",
"codec_type": "audio",
"codec_time_base": "1/44100",
"codec_tag_string": "[0][0][0][0]",
"codec_tag": "0x0000",
"sample_fmt": "fltp",
"sample_rate": "44100",
"channels": 2,
"channel_layout": "stereo",
"bits_per_sample": 0,
"r_frame_rate": "0/0",
"avg_frame_rate": "0/0",
"time_base": "1/28224000",
"duration_ts": 305349201,
"duration": "10.818778",
"bit_rate": "27734",
"disposition": {
"default": 0,
"dub": 0,
"original": 0,
"comment": 0,
"lyrics": 0,
"karaoke": 0,
"forced": 0,
"hearing_impaired": 0,
"visual_impaired": 0,
"clean_effects": 0,
"attached_pic": 0
}
}
],
"format": {
"filename": "your-input-file.mp4",
"nb_streams": 1,
"nb_programs": 0,
"format_name": "aac",
"format_long_name": "raw ADTS AAC (Advanced Audio Coding)",
"duration": "10.818778",
"size": "37506",
"bit_rate": "27734",
"probe_score": 51
}
}

you can find the duration information in format section, works both for video and audio

Best Solution: cut the export do get something like 00:05:03.22

ffmpeg -i input 2>&1 | grep Duration | cut -c 13-23

If you want to retrieve the length (and possibly all other metadata) from your media file with ffmpeg by using a python script you could try this:

import subprocess
import json


input_file  = "< path to your input file here >"


metadata = subprocess.check_output(f"ffprobe -i {input_file} -v quiet -print_format json -show_format -hide_banner".split(" "))


metadata = json.loads(metadata)
print(f"Length of file is: {float(metadata['format']['duration'])}")
print(metadata)

Output:

Length of file is: 7579.977143


{
"streams": [
{
"index": 0,
"codec_name": "mp3",
"codec_long_name": "MP3 (MPEG audio layer 3)",
"codec_type": "audio",
"codec_time_base": "1/44100",
"codec_tag_string": "[0][0][0][0]",
"codec_tag": "0x0000",
"sample_fmt": "fltp",
"sample_rate": "44100",
"channels": 2,
"channel_layout": "stereo",
"bits_per_sample": 0,
"r_frame_rate": "0/0",
"avg_frame_rate": "0/0",
"time_base": "1/14112000",
"start_pts": 353600,
"start_time": "0.025057",
"duration_ts": 106968637440,
"duration": "7579.977143",
"bit_rate": "320000",
...
...

# Returns duration (in seconds) of a video $1 (uses ffmpeg).
get_video_duration() {
OUTPUT=$(ffmpeg -i "$1" -vframes 1 -f rawvideo -y /dev/null 2>&1) ||
{ debug -e "get_video_duration: error running ffmpeg:\n$OUTPUT"; return 1; }
DURATION=$(echo "$OUTPUT" | grep -m1 "^[[:space:]]*Duration:" |
cut -d":" -f2- | cut -d"," -f1 | sed "s/[:\.]/ /g") ||
{ debug -e "get_video_duration: error parsing duration:\n$OUTPUT"; return 1; }
read HOURS MINUTES SECONDS DECISECONDS <<< "$DURATION"
echo $((10#$HOURS * 3600 + 10#$MINUTES * 60 + 10#$SECONDS))
}

Usage:

DURATION=$(get_video_duration "$VIDEO")

This is my really simple solution using ffmpeg and awk. The output of ffmpeg -i file.mp3 contain a string Duration: 00:00:04.80, bitrate: 352 kb/s. Just simply using awk:

ffmpeg -i file.mp3 |& awk '/Duration:/ {print $2}'

I can print the expected result: 00:00:04.80

use ffprobe which is used to extract metadata from media files

install ffprobe with pip

pip install ffprobe-python

`from subprocess import check_output

file_name = "video1.mp4"

command = str(check_output('ffprobe -i "'+file_name+'" 2>&1 |grep "Duration"',shell=True))
#output: b' Duration: 00:17:56.62, start: 0.000000, bitrate: 397 kb/s\n'

#split the duration in hh:mm:ss format co = a.split(",")[0].split("Duration:")[1].strip()

h, m, s = a.split(':') duration = int(h) * 3600 + int(m) * 60 + float(s)

print(duration)`

No grepping or anything like that required. Just put this one command and you will get precise time in microseconds!

ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 file.mp4

From ffmpeg docs https://trac.ffmpeg.org/wiki/FFprobeTips