ffprobe | ShowFrames | Packet Size | Divide | Add

Question

I am running this statement in shell

for file in /path/to/files/*.mp4; do ffprobe -show_frames $file | grep "pkt_size" > ${file}.txt

done

It would be great if I could get this information too;

When I grep pkt_size row with numbers then I want script to - divide every pkt_size number with 100,
then add (sum) pkt_size row numbers every after 50 rows.

1. There is no `done` at the end of `for` loop. 2. Use correct formatting for source code. — Arkadiusz Drabczyk, May 07 '15 at 14:03
There is no "data" filed in -show_frames output. Which field do you want to grep? If you can explain what exactly you want to do then may be can suggest different approach. — Alam, May 07 '15 at 14:15
well greping the data was an example - I have edited the script again. 1) Search all the mp4s in the folder, 2) Do ffprobe -show_frames 3) Create individual output file for every video in the folder 4) Take the "pkt_size" row from the output 5) Add(sum) pkt_size numbers after every 50 rows (set of 50 rows) 6) finally, divide by 1000 with every sum(step 5) — Ben, May 07 '15 at 14:46
No need for `grep`: `ffprobe -v error -show_entries frame=pkt_size -of default=noprint_wrappers=1:nokey=1 input.mp4` — llogan, May 07 '15 at 18:47
Lord could you explain little bit pls. Just don't understand how it's adding 50 rows and then diving ..? — Ben, May 07 '15 at 20:15

score 1 · Answer 1 · edited May 23 '17 at 10:26

I already showed you in another answer how to iterate all files and append results. This is how you would go about calculating stuff in bash for one file, using @LordNeckbeard's ffprobe command.

Your homework is to modify and integrate the two answers.

#!/bin/bash

file=/path/to/file.mp4

if [ ! -f $file ]; then
    echo Error: File not found
    exit 1
fi

pkt_sizes=$(ffprobe -show_entries frame=pkt_size -of default=noprint_wrappers=1:nokey=1 -i $file -loglevel 0)

function print_sum {
    #use `bc` for floating point operations 
    sum=$(echo "scale=${precision};${sum}/100" | bc -l)
    echo "SUM("$start","$i")="$sum
}

i=1
start=1
sum=0
precision=3

#compute/print sum every 50 packets
for size in $pkt_sizes; do  
    (( sum+= size ))

    if (( $i % 50 == 0 )); then     
        print_sum
        sum=0
        start=$(( i + 1 ))
    fi 

    (( i++ ))   
done;

#sum last packets (n < 50)
if (( "$start" < "$i" )); then  
    (( i-- ))
    print_sum
fi

This is more than enough to get you started with shell arithmetic so please refer to the documentation for further questions.

Hi Aergistal, Many thanks for your efforts. Really appreciate it. I am really new to this shell programming. That's please ignore my silly questions. I saved your code with correct path/to/file/file.mp4 But this is what happenning, Ben@ben-VirtualBox ~/Downlaods $ which bash /bin/bash Ben@ben-VirtualBox ~/Downlaods $ chmod +x script.sh Command not found Ben@ben-VirtualBox ~/Downlaods $ script.sh Command not found — Ben, May 08 '15 at 13:19

ffprobe | ShowFrames | Packet Size | Divide | Add

1 Answers1