Digital Forensics Challenge 2021 Writeup (308— Find Forged Record)
This is the writeup I submitted for problem 308 on Digital Forensics Challenge 2021 held by Korea Institute of Information Security & Cryptology (KIISC). My team name is trying2learn and the score I got from this problem is 215 out of 300. This writeup was posted here after the deadline of this problem for fair competition.
Instructions
Description
Verification of the authenticity of voice data is very important in forensic investigation. Here are recording files extracted from the suspect’s mobile, pc, and wearable devices. Victims raised suspicions that the audio recordings were tampered with. As a digital forensic investigator, analyze the submitted evidence and whether the files had been tampered with.
Questions
File Given
Submitted_Media.ad1
Tool Used
AccessData FTK Imager, MediaInfo, Python, and Visual Studio Code are the tools that will be used to answer this problem.
Answer
The first thing we must do to solve all the problems is extracting Media1, Media2, Media3, and Media4 folders from Submitted_Media.ad1. We will use AccessData FTK Imager to help us open Submitted_Media.ad1 file and extract all folders we need. We will go to File -> Add Evidence Item -> Image File -> (browse for Submitted_Media.ad1 file) -> Finish. After that, if we look at the evidence tree and analyze it then Media1, Media2, Media3, and Media4 folders will be found. We need to extract those folders. We can extract it by right clicking on the folder then choose ‘Export Files’. Next, we will browse for the destination. After all those folders are extracted, we can use it to solve all the problems. Here, we will use MediaInfo to help us solve all the problems.
In order to solve the first problem, we need to open ‘Samsung Note 2.m4a’ file using MediaInfo. After that, we will go to View -> Text to make it easier to read. The result is shown in Figure 1.
From the figure above we can see a lot information about the file. We can use the information to answer the first question because the information we got cover all information needed to answer the first question.
Codec Information: Advanced Audio Codec Low Complexity (mp4a)
Duration: 55 s 983 ms
Overall Bit Rate: 127 kb/s
Sampling Rate: 44.1 kHz
Frame Rate: 43.066 FPS (1024 SPF)
Title: SoundHandle
More information can be seen in Figure 1.
First Problem Solved
Next, to answer the second problem, we will analyze all files stored on Media 2 folder by opening each file stored there using MediaInfo. After opening the file, we will go to View -> Text again to make it easier to read.
The first file on Media2 folder that will be opened is ‘Gear S3 1_W_20210823_172418.m4a’. The result is shown in Figure 2.
As we can see from the figure above, there is no information about encoding date. Mostly, the value of encoding date will be the same as recording date. Here, we will assume that the encoding date and recording date are the same because there is no specific information about the recording date. The absence of encoding date indicates that the file was tampered. Fortunately, we can still find the encoding date and recording date manually by looking at the file name because the file name is in default (not renamed). Two last parameters on the file name show us the recording date which is 20210823_172418. The first parameter shows the date and the second one shows the time. The timestamp format is in local time format. If we try to look at the other file’s information (Gear S3 3_W_20210823_174557.m4a) shown in Figure 3 and compare the file name with the encoding date, we can see that the timestamp on the file is in UTC+9 format. So, we can convert the timestamp on the file to UTC format. Although we can find the encoding date from the file name, the absence of the encoding date as I stated before still indicates that the file was tampered. Furthermore, we can see that Lavf58.29.100 was used. The use of this application also indicates that the file was tampered. So, we can conclude that the file was tampered.
Below is the information of ‘Gear S3 1_W_20210823_172418.m4a’ needed to answer the second problem.
Recording date: 2021–08–23 08:24:18 UTC
The number of channels: 2 channels
Encoding date: 2021–08–23 08:24:18 UTC
Playback time: -
Application used: Lavf58.29.100
Frame rate: 23.438 FPS (1024 SPF)
Codec type: Advanced Audio Codec Low Complexity (mp4a)
Metadata of multimedia container file:
Complete name: Media 2\Gear S3 1_W_20210823_172418.m4a
Format: MPEG-4
Format profile: Apple audio with iTunes info
Codec ID: M4A (isom/iso2)
File size: 274 KiB
Duration: 57 s 515 ms
Overall bit rate mode: Constant
Overall bit rate: 39.1 kb/s
Writing application: Lavf58.29.100
Unique ID: -
More information can be seen in Figure 2.
The second file on Media2 folder that will be opened is ‘Gear S3 3_W_20210823_174557.m4a’. The result is shown in Figure 3.
From the figure above, we can see that there is information about the encoding date. The encoding date on the file container and audio stream are match each other. This means that the file was not tampered. Furthermore, there is no writing application used here. This means that no application was used to tamper the file. So, we can conclude that ‘Gear S3 3_W_20210823_174557.m4a’ was not tampered.
Below is the information of ‘Gear S3 3_W_20210823_174557.m4a’ needed to answer the second problem.
Recording date: 2021–08–23 08:45:57 UTC
The number of channels: 1 channel
Encoding date: 2021–08–23 08:45:57 UTC
Playback time: -
Application used: -
Frame rate: 15.625 FPS (1024 SPF)
Codec type: Advanced Audio Codec Low Complexity (mp4a)
Metadata of multimedia container file:
Complete name: Media 2\Gear S3 3_W_20210823_174557.m4a
Format: MPEG-4
Format profile: Base Media / Version 2
Codec ID: mp42 (mp42/mp41/isom/iso2)
File size: 561 KiB
Duration: 48 s 512 ms
Overall bit rate mode: Constant
Overall bit rate: 94.7 kb/s
Encoded date: UTC 2021–08–23 08:45:57
Tagged date: UTC 2021–08–23 08:45:57
Unique ID: -
More information can be seen in Figure 3.
The third file on Media2 folder that will be opened is ‘Gear S3 5_W_20210823_175704.m4a’. The result is shown in Figure 4.
From the figure above, we can see that there is information about encoding date for both container and audio stream, but the encoding date seems unusual. Furthermore, we can see that there are two application used here which is PotEncoder and LAME. Both applications are used to do encoding. PotEncoder encode the container and LAME encode the audio stream. This means that ‘Gear S3 5_W_20210823_175704.m4a’ was tampered. Fortunately, we can still find the recording date using the same method we use to find the recording date for ‘Gear S3 1_W_20210823_172418.m4a’.
Below is the information of ‘Gear S3 5_W_20210823_175704.m4a’ needed to answer the second problem.
Recording date: 2021–08–23 08:57:04 UTC
The number of channels: 2 channels
Encoding date: 1970–01–01 00:00:00 UTC
Playback time: -
Application used: PotEncoder, LAME
Frame rate: -
Codec type: Layer 3 (MP3)
Metadata of multimedia container file:
Complete name: Media 2\Gear S3 5_W_20210823_175704.m4a
Format: MPEG-4
Format profile: Base Media
Codec ID: isom (mp41)
File size: 497 KiB
Duration: 1 min 7 s
Overall bit rate mode: Variable
Overall bit rate: 60.5 kb/s
Encoded date: UTC 1970–01–01 00:00:00
Tagged date: UTC 1970–01–01 00:00:00
Writing application: PotEncoder
Unique ID: -
More information can be seen in Figure 4.
The fourth file on Media2 folder that will be opened is ‘Samsung Note 10 1.m4a’. The result is shown in Figure 5.
From the figure above, we can see that there is information about encoding date. However, the encoding date between the file container and audio stream are different. Furthermore, the encoding date on the file container is the same as tagged date on the audio stream. The interval between encoded date and tagged date on the audio stream is unusual because it is too long which is 6 days. So, we can conclude that ‘Samsung Note 10 1.m4a’ was tampered. If we search on the internet, the audio playback time for Samsung Note 10 is up to 50 hours.
Below is the information of ‘Samsung Note 10 1.m4a’ needed to answer the second problem.
Recording date: 2021–08–23 11:52:53 UTC
The number of channels: 1 channel
Encoding date: 2021–08–23 11:52:53 UTC (Audio Stream), 2021–08–29 05:30:52 UTC (Container)
Playback time: up to 50 hours (Samsung Note 10)
Application used: -
Frame rate: 43.066 FPS (1024 SPF)
Codec type: Advanced Audio Codec Low Complexity (mp4a)
Metadata of multimedia container file:
Complete name: Media 2\Samsung Note 10 1.m4a
Format: MPEG-4
Format profile: 3GPP Media Release 4
Codec ID: 3gp4 (isom/3gp4)
File size: 770 KiB
Duration: 46 s 486 ms
Overall bit rate mode: Constant
Overall bit rate: 136 kb/s
Encoded date: UTC 2021–08–29 05:30:52
Tagged date: UTC 2021–08–29 05:30:52
book: bkmk
Unique ID: -
More information can be seen in Figure 5.
The fifth file on Media2 folder that will be opened is ‘Samsung Note 10 2.m4a’. The result is shown in Figure 6.
From the figure above, we can see that there is information about the encoding date and nothing strange. The file container and audio stream encoding dates match each other. Although there is no information about the application used to record the audio, we can still conclude that ‘Samsung Note 10 2.m4a’ was not tampered. Probably, this audio was recorded using android default voice recorder.
Below is the information of ‘Samsung Note 10 2.m4a’ needed to answer the second problem.
Recording date: 2021–08–23 11:55:43 UTC
The number of channels: 1 channel
Encoding date: 2021–08–23 11:55:43 UTC
Playback time: up to 50 hours (Samsung Note 10)
Application used: -
Frame rate: 43.066 FPS (1024 SPF)
Codec type: Advanced Audio Codec Low Complexity (mp4a)
Metadata of multimedia container file:
Complete name: Media 2\Samsung Note 10 2.m4a
Format: MPEG-4
Format profile: 3GPP Media Release 4
Codec ID: 3gp4 (isom/3gp4)
File size: 1 005 KiB
Duration: 1 min 1 s
Overall bit rate mode: Constant
Overall bit rate: 134 kb/s
Encoded date: UTC 2021–08–23 11:55:43
Tagged date: UTC 2021–08–23 11:55:43
book: bkmk
com.android.version: 11
Unique ID: -
More information can be seen in Figure 6.
Second Problem Solved
Next, we will solve the third problem using the same method we used before to solve the second problem.
The first file on Media3 folder that will be opened is ‘iPhone 6S 1.m4a’. The result is shown in Figure 7.
From the figure above, we can see that there is information about encoding date. The file container and audio stream encoding dates match each other. Nothing strange with the encoding date indicates that the file was not tampered. Furthermore, we can see that the writing application used is com.apple.VoiceMemos (iPhone (null)). This indicates the use of voice memos which is the default voice recorder app on iPhone. Voice memos is the application that generates this file So, we can conclude that ‘iPhone 6S 1.m4a’ was not tampered. We can also see that there is an information about the recorded date. Therefore, we will not use encoding date as recording date for this situation because recorded date as shown in Figure 7 is more reliable. If we search on the internet, the audio playback time for iPhone 6s is up to 50 hours.
Below is the information of ‘iPhone 6S 1.m4a’ needed to answer the third problem.
Recording date: 2021–08–23 09:51:41 UTC
The number of channels: 1 channel
Encoding date: 2021–08–28 10:23:16 UTC
Playback time: up to 50 hours (iPhone 6s)
Application used: com.apple.VoiceMemos (iPhone (null))
Frame rate: 43.066 FPS (1024 SPF)
Codec type: Advanced Audio Codec Low Complexity (mp4a)
Metadata of multimedia container file:
Complete name: Media 3\iPhone 6S 1.m4a
Format: MPEG-4
Format profile: Apple audio with iTunes info
Codec ID: M4A (M4A /isom/mp42)
File size: 1.95 MiB
Duration: 1 min 10 s
Overall bit rate mode: Constant
Overall bit rate: 230 kb/s
Track name: iPhone 1
Recorded date: 2021–08–23T09:51:41Z
Encoded date: UTC 2021–08–28 10:23:16
Tagged date: UTC 2021–08–28 10:23:17
Writing application: com.apple.VoiceMemos (iPhone (null))
voice-memo-uuid: 9D335095-A748–477C-916F-9A695AE431AF
Unique ID: 9D335095-A748–477C-916F-9A695AE431AF
More information can be seen in Figure 7.
The second file on Media3 folder that will be opened is ‘iPhone 6S 2.m4a’. The result is shown in Figure 8.
From the figure above, we can see that there is no information related to encoding date. We can also see that the writing application used is Lavf58.29.100. This indicates that the file was tampered using Lavf58.29.100.
Below is the information of ‘iPhone 6S 2.m4a’ needed to answer the third problem.
Recording date: -
The number of channels: 1 channel
Encoding date: -
Playback time: up to 50 hours (iPhone 6s)
Application used: Lavf58.29.100
Frame rate: 46.875 FPS (1024 SPF)
Codec type: Advanced Audio Codec Low Complexity (mp4a)
Metadata of multimedia container file:
Complete name: Media 3\iPhone 6S 2.m4a
Format: MPEG-4
Format profile: Apple audio with iTunes info
Codec ID: M4A (isom/iso2)
File size: 434 KiB
Duration: 55 s 275 ms
Overall bit rate mode: Constant
Overall bit rate: 64.3 kb/s
Track name: iPhone 2
Writing application: Lavf58.29.100
Unique ID: -
More information can be seen in Figure 8.
The third file on Media3 folder that will be opened is ‘iPhone 6S 3.m4a’. The result is shown in Figure 9.
From the figure above, we can see that there is information about encoding date. The file container and audio stream encoding date are match each other. Furthermore, com.apple.VoiceMemos (iPhone (null)) was used again here as the writing application. So, we can conclude that this file was not tampered. We can also see that the encoding date is the same as the recording date.
Below is the information of ‘iPhone 6S 3.m4a’ needed to answer the third problem.
Recording date: 2021–08–23 09:56:13 UTC
The number of channels: 1 channel
Encoding date: 2021–08–23 09:56:13 UTC
Playback time: up to 50 hours (iPhone 6s)
Application used: com.apple.VoiceMemos (iPhone (null))
Frame rate: 46.875 FPS (1024 SPF)
Codec type: Advanced Audio Codec Low Complexity (mp4a)
Metadata of multimedia container file:
Complete name: Media 3\iPhone 6S 3.m4a
Format: MPEG-4
Format profile: Apple audio with iTunes info
Codec ID: M4A (M4A /isom/mp42)
File size: 623 KiB
Duration: 1 min 16 s
Overall bit rate mode: Constant
Overall bit rate: 66.6 kb/s
Track name: iPhone 3
Recorded date: 2021–08–23T09:56:13Z
Encoded date: UTC 2021–08–23 09:56:13
Tagged date: UTC 2021–08–23 09:57:31
Writing application: com.apple.VoiceMemos (iPhone (null))
voice-memo-uuid: C97354C4-B526–4782–99C5–822515431D4B
Unique ID: C97354C4-B526–4782–99C5–822515431D4B
More information can be seen in Figure 9.
The fourth file on Media3 that will be opened is ‘iPhone 6S 4.m4a’. The result is shown in Figure 10.
From the figure above, we can see that there is information about encoding date. There is a slight difference between encoding date on the file container and audio stream, but it can still be tolerated because it is only 1 second defference. We can also see that com.apple.VoiceMemos (iPhone (null)) was used again as the writing application. So, we can conclude that ‘iPhone 6S 4.m4a’ was not tampered.
Below is the information of ‘iPhone 6S 4.m4a’ needed to answer the third problem.
Recording date: 2021–08–23 10:02:53 UTC
The number of channels: 1 channel
Encoding date: 2021–08–23 10:06:08 UTC (file container), 2021–08–23 10:06:09 UTC (Audio stream)
Playback time: up to 50 hours (iPhone 6s)
Application used: com.apple.VoiceMemos (iPhone (null))
Frame rate: 43.066 FPS (1024 SPF)
Codec type: Advanced Audio Codec Low Complexity (mp4a)
Metadata of multimedia container file:
Complete name: Media 3\iPhone 6S 4.m4a
Format: MPEG-4
Format profile: Apple audio with iTunes info
Codec ID: M4A (M4A /isom/mp42)
File size: 2.64 MiB
Duration: 1 min 36 s
Overall bit rate mode: Constant
Overall bit rate: 229 kb/s
Track name: iPhone 4
Recorded date: 2021–08–23T10:02:53Z
Encoded date: UTC 2021–08–23 10:06:08
Tagged date: UTC 2021–08–23 10:06:11
Writing application: com.apple.VoiceMemos (iPhone (null))
voice-memo-uuid: D6840102–23AF-4C08-ACFC-9794C320836D
Unique ID: D6840102–23AF-4C08-ACFC-9794C320836D
More information can be seen in Figure 10.
The fifth file on Media3 that will be opened is ‘MacbookPro 1.m4a’. The result is shown in Figure 11.
From the figure above, we can see that there is no information about encoding date and recording date. Furthermore, Lavf59.4.101 is the writing application used to generate this file. So, we can conclude that ‘MacbookPro 1.m4a’ was tampered.
Below is the information of ‘MacbookPro 1.m4a’ needed to answer the third problem.
Recording date: -
The number of channels: 1 channel
Encoding date: -
Playback time: -
Application used: Lavf59.4.101
Frame rate: -
Codec type: Apple Lossless Audio Codec
Metadata of multimedia container file:
Complete name: Media 3\MacbookPro 1.m4a
Format: MPEG-4
Format profile: Apple audio with iTunes info
Codec ID: M4A (M4A /isom/iso2)
File size: 6.34 MiB
Duration: 45 s 951 ms
Overall bit rate mode: Variable
Overall bit rate: 1 158 kb/s
Track name: Macbook Pro 1
Writing application: Lavf59.4.101
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Unique ID: -
More information can be seen in Figure 11.
The sixth file on Media3 that will be opened is ‘MacbookPro 2.m4a’. The result is shown in Figure 12.
From the figure above, we can see that there is information about encoding date. The file container and audio stream encoding dates match each other. Furthermore, we can see the use of Voice Memos here which is the default voice recorder app for Macbook. So, we can conclude that the file was not tampered. There is no information about recording date like before. So, we will assume that the encoding date is the same as recording date.
Below is the information of ‘MacbookPro 2.m4a’ needed to answer the third problem.
Recording date: 2021–08–23 11:28:03 UTC
The number of channels: 1 channel
Encoding date: 2021–08–23 11:28:03 UTC
Playback time: -
Application used: com.apple.VoiceMemos (Mac OS X 10.15.7)
Frame rate: 46.875 FPS (1024 SPF)
Codec type: Advanced Audio Codec Low Complexity (mp4a)
Metadata of multimedia container file:
Complete name: Media 3\MacbookPro 2.m4a
Format: MPEG-4
Format profile: Apple audio with iTunes info
Codec ID: M4A (M4A /isom/mp42)
File size: 409 KiB
Duration: 50 s 348 ms
Overall bit rate mode: Constant
Overall bit rate: 66.6 kb/s
Track name: Macbook Pro 2
Encoded date: UTC 2021–08–23 11:28:03
Tagged date: UTC 2021–08–23 11:28:54
Writing application: com.apple.VoiceMemos (Mac OS X 10.15.7)
voice-memo-uuid: 27013621–6644–45CB-8F7F-D4158479992B
Unique ID: 27013621–6644–45CB-8F7F-D4158479992B
More information can be seen in Figure 12.
The seventh file on Media3 that will be opened is ‘MacbookPro 3.m4a’. The result is shown in Figure 13.
From the figure above, we can see that there is no information about encoding date and recording date. Furthermore, Lavf55.33.100 is the writing application used to generate this file. So, we can conclude that ‘MacbookPro 3.m4a’ was tampered.
Below is the information of ‘MacbookPro 3.m4a’ needed to answer the third problem.
Recording date: -
The number of channels: 1 channel
Encoding date: -
Playback time: -
Application used: Lavf55.33.100
Frame rate: 46.875 FPS (1024 SPF)
Codec type: Advanced Audio Codec Low Complexity (mp4a)
Metadata of multimedia container file:
Complete name: Media 3\MacbookPro 3.m4a
Format: MPEG-4
Format profile: Apple audio with iTunes info
Codec ID: M4A (isom/iso2)
File size: 2.08 MiB
Duration: 1 min 27 s
Overall bit rate mode: Constant
Overall bit rate: 199 kb/s
Track name: Macbook Pro 3
Writing application: Lavf55.33.100
Unique ID: -
More information can be seen in Figure 13.
Third Problem Solved.
Next, we are asked to develop a script or tool that can distinguish between normal voice data and forged voice data recorded on Android and iOS. From the result of our analysis on Q2 and Q3, we can conclude that the first thing that indicates forged voice data is the absence of the encoded_date key on file container and audio stream. If there is information about the encoded date, we must check if there is information about writing application (encoded application) used. If there is information about writing application (encoded application) used, we must check the value. Voice Memos (com.apple.VoiceMemos) is the default audio recording apps on iOS device. So, if the writing application (encoded application) used is com.apple.VoiceMemos then it means that the audio file is normal voice data. Meanwhile, on Android phone device, the normal voice data will not generate writing_application (encoded application) key, but it will generate a key named comandroidversion (com.android.version). So, if the value of writing_application key is not com.apple.VoiceMemos then most likely the audio file has been forged. On Android wearable device, there is no writing_application key or comandroidversion key. The indication of normal voice data recorded on Android wearable device is that the encoded date of the file container and the audio stream must be the same and no writing application is used.
We will develop the script based on what we have analyzed in Q2 and Q3 as what I have stated before. In order to develop the script, I will use python as the programming language and Visual Studio Code as the text editor. We will select the pyhton we installed as the interpreter on Visual Studio Code. We also need to install MediaInfo library to help us develop the code easier. To install mediainfo library, we will use the command ‘python -m pip install pymediainfo’ on the Visual Studio Code terminal. Now, we are ready to code. Below is the code I develop to answer the fourth problem. I named the file checkAudio.py.
Using checkAudio.py, we can choose to check one audio file inputted or all audio file stored in a directory/folder inputted. This script will only check the file which contains audio stream. After that, we will try to use checkAudio.py script to check the audio file on Media2 and Media3 folders. We will run it on Visual Studio Code by pressing F5 and choose ‘Python File’. After that we will input ‘d’ because we want to choose directory option, so we do not need to select the file one by one. Then, we will input the directory/folder path. The results are shown below.
The two results above match with the answers we got on Q2 and Q3 before. So, we can conclude that ‘checkAudio.py’ works well and can be used to answer the fourth problem.
We will run ‘checkAudio.py’ to check all audio files stored on Media4 folder. The result is shown in Figure 19.
Fourth Problem Solved
Summary:
1. Samsung Note 2.m4a (Media1 folder)
Codec Information: Advanced Audio Codec Low Complexity (mp4a)
Duration: 55 s 983 ms
Overall Bit Rate: 127 kb/s
Sampling Rate: 44.1 kHz
Frame Rate: 43.066 FPS (1024 SPF)
Title: SoundHandle
More information can be seen below.
2. Media2 folder
- Gear S3 1_W_20210823_172418.m4a was tampered
Recording date: 2021–08–23 08:24:18 UTC
The number of channels: 2 channels
Encoding date: 2021–08–23 08:24:18 UTC
Playback time: -
Application used: Lavf58.29.100
Frame rate: 23.438 FPS (1024 SPF)
Codec type: Advanced Audio Codec Low Complexity (mp4a)
Metadata of multimedia container file:
Complete name: Media 2\Gear S3 1_W_20210823_172418.m4a
Format: MPEG-4
Format profile: Apple audio with iTunes info
Codec ID: M4A (isom/iso2)
File size: 274 KiB
Duration: 57 s 515 ms
Overall bit rate mode: Constant
Overall bit rate: 39.1 kb/s
Writing application: Lavf58.29.100
Unique ID: -
More information can be seen below.
- Gear S3 3_W_20210823_174557.m4a
Recording date: 2021–08–23 08:45:57 UTC
The number of channels: 1 channel
Encoding date: 2021–08–23 08:45:57 UTC
Playback time: -
Application used: -
Frame rate: 15.625 FPS (1024 SPF)
Codec type: Advanced Audio Codec Low Complexity (mp4a)
Metadata of multimedia container file:
Complete name: Media 2\Gear S3 3_W_20210823_174557.m4a
Format: MPEG-4
Format profile: Base Media / Version 2
Codec ID: mp42 (mp42/mp41/isom/iso2)
File size: 561 KiB
Duration: 48 s 512 ms
Overall bit rate mode: Constant
Overall bit rate: 94.7 kb/s
Encoded date: UTC 2021–08–23 08:45:57
Tagged date: UTC 2021–08–23 08:45:57
Unique ID: -
More information can be seen below.
- Gear S3 5_W_20210823_175704.m4a
Recording date: 2021–08–23 08:57:04 UTC
The number of channels: 2 channels
Encoding date: 1970–01–01 00:00:00 UTC
Playback time: -
Application used: PotEncoder, LAME
Frame rate: -
Codec type: Layer 3 (MP3)
Metadata of multimedia container file:
Complete name: Media 2\Gear S3 5_W_20210823_175704.m4a
Format: MPEG-4
Format profile: Base Media
Codec ID: isom (mp41)
File size: 497 KiB
Duration: 1 min 7 s
Overall bit rate mode: Variable
Overall bit rate: 60.5 kb/s
Encoded date: UTC 1970–01–01 00:00:00
Tagged date: UTC 1970–01–01 00:00:00
Writing application: PotEncoder
Unique ID: -
More information can be seen below.
- Samsung Note 10 1
Recording date: 2021–08–23 11:52:53 UTC
The number of channels: 1 channel
Encoding date: 2021–08–23 11:52:53 UTC (Audio Stream), 2021–08–29 05:30:52 UTC (Container)
Playback time: up to 50 hours (Samsung Note 10)
Application used: -
Frame rate: 43.066 FPS (1024 SPF)
Codec type: Advanced Audio Codec Low Complexity (mp4a)
Metadata of multimedia container file:
Complete name: Media 2\Samsung Note 10 1.m4a
Format: MPEG-4
Format profile: 3GPP Media Release 4
Codec ID: 3gp4 (isom/3gp4)
File size: 770 KiB
Duration: 46 s 486 ms
Overall bit rate mode: Constant
Overall bit rate: 136 kb/s
Encoded date: UTC 2021–08–29 05:30:52
Tagged date: UTC 2021–08–29 05:30:52
book: bkmk
Unique ID: -
More information can be seen below.
- Samsung Note 10 2
Recording date: 2021–08–23 11:55:43 UTC
The number of channels: 1 channel
Encoding date: 2021–08–23 11:55:43 UTC
Playback time: up to 50 hours (Samsung Note 10)
Application used: -
Frame rate: 43.066 FPS (1024 SPF)
Codec type: Advanced Audio Codec Low Complexity (mp4a)
Metadata of multimedia container file:
Complete name: Media 2\Samsung Note 10 2.m4a
Format: MPEG-4
Format profile: 3GPP Media Release 4
Codec ID: 3gp4 (isom/3gp4)
File size: 1 005 KiB
Duration: 1 min 1 s
Overall bit rate mode: Constant
Overall bit rate: 134 kb/s
Encoded date: UTC 2021–08–23 11:55:43
Tagged date: UTC 2021–08–23 11:55:43
book: bkmk
com.android.version: 11
Unique ID: -
More information can be seen below.
3. Media3 folder
- iPhone 6S 1.m4a
Recording date: 2021–08–23 09:51:41 UTC
The number of channels: 1 channel
Encoding date: 2021–08–28 10:23:16 UTC
Playback time: up to 50 hours (iPhone 6s)
Application used: com.apple.VoiceMemos (iPhone (null))
Frame rate: 43.066 FPS (1024 SPF)
Codec type: Advanced Audio Codec Low Complexity (mp4a)
Metadata of multimedia container file:
Complete name: Media 3\iPhone 6S 1.m4a
Format: MPEG-4
Format profile: Apple audio with iTunes info
Codec ID: M4A (M4A /isom/mp42)
File size: 1.95 MiB
Duration: 1 min 10 s
Overall bit rate mode: Constant
Overall bit rate: 230 kb/s
Track name: iPhone 1
Recorded date: 2021–08–23T09:51:41Z
Encoded date: UTC 2021–08–28 10:23:16
Tagged date: UTC 2021–08–28 10:23:17
Writing application: com.apple.VoiceMemos (iPhone (null))
voice-memo-uuid: 9D335095-A748–477C-916F-9A695AE431AF
Unique ID: 9D335095-A748–477C-916F-9A695AE431AF
More information can be seen below.
- iPhone 6S 2.m4a
Recording date: -
The number of channels: 1 channel
Encoding date: -
Playback time: up to 50 hours (iPhone 6s)
Application used: Lavf58.29.100
Frame rate: 46.875 FPS (1024 SPF)
Codec type: Advanced Audio Codec Low Complexity (mp4a)
Metadata of multimedia container file:
Complete name: Media 3\iPhone 6S 2.m4a
Format: MPEG-4
Format profile: Apple audio with iTunes info
Codec ID: M4A (isom/iso2)
File size: 434 KiB
Duration: 55 s 275 ms
Overall bit rate mode: Constant
Overall bit rate: 64.3 kb/s
Track name: iPhone 2
Writing application: Lavf58.29.100
Unique ID: -
More information can be seen below.
- iPhone 6S 3.m4a
Recording date: 2021–08–23 09:56:13 UTC
The number of channels: 1 channel
Encoding date: 2021–08–23 09:56:13 UTC
Playback time: up to 50 hours (iPhone 6s)
Application used: com.apple.VoiceMemos (iPhone (null))
Frame rate: 46.875 FPS (1024 SPF)
Codec type: Advanced Audio Codec Low Complexity (mp4a)
Metadata of multimedia container file:
Complete name: Media 3\iPhone 6S 3.m4a
Format: MPEG-4
Format profile: Apple audio with iTunes info
Codec ID: M4A (M4A /isom/mp42)
File size: 623 KiB
Duration: 1 min 16 s
Overall bit rate mode: Constant
Overall bit rate: 66.6 kb/s
Track name: iPhone 3
Recorded date: 2021–08–23T09:56:13Z
Encoded date: UTC 2021–08–23 09:56:13
Tagged date: UTC 2021–08–23 09:57:31
Writing application: com.apple.VoiceMemos (iPhone (null))
voice-memo-uuid: C97354C4-B526–4782–99C5–822515431D4B
Unique ID: C97354C4-B526–4782–99C5–822515431D4B
More information can be seen below.
- iPhone 6S 4.m4a
Recording date: 2021–08–23 10:02:53 UTC
The number of channels: 1 channel
Encoding date: 2021–08–23 10:06:08 UTC (file container), 2021–08–23 10:06:09 UTC (Audio stream)
Playback time: up to 50 hours (iPhone 6s)
Application used: com.apple.VoiceMemos (iPhone (null))
Frame rate: 43.066 FPS (1024 SPF)
Codec type: Advanced Audio Codec Low Complexity (mp4a)
Metadata of multimedia container file:
Complete name: Media 3\iPhone 6S 4.m4a
Format: MPEG-4
Format profile: Apple audio with iTunes info
Codec ID: M4A (M4A /isom/mp42)
File size: 2.64 MiB
Duration: 1 min 36 s
Overall bit rate mode: Constant
Overall bit rate: 229 kb/s
Track name: iPhone 4
Recorded date: 2021–08–23T10:02:53Z
Encoded date: UTC 2021–08–23 10:06:08
Tagged date: UTC 2021–08–23 10:06:11
Writing application: com.apple.VoiceMemos (iPhone (null))
voice-memo-uuid: D6840102–23AF-4C08-ACFC-9794C320836D
Unique ID: D6840102–23AF-4C08-ACFC-9794C320836D
More information can be seen below.
- MacbookPro 1.m4a
Recording date: -
The number of channels: 1 channel
Encoding date: -
Playback time: -
Application used: Lavf59.4.101
Frame rate: -
Codec type: Apple Lossless Audio Codec
Metadata of multimedia container file:
Complete name: Media 3\MacbookPro 1.m4a
Format: MPEG-4
Format profile: Apple audio with iTunes info
Codec ID: M4A (M4A /isom/iso2)
File size: 6.34 MiB
Duration: 45 s 951 ms
Overall bit rate mode: Variable
Overall bit rate: 1 158 kb/s
Track name: Macbook Pro 1
Writing application: Lavf59.4.101
Unique ID: -
More information can be seen below.
- MacbookPro 2.m4a
Recording date: 2021–08–23 11:28:03 UTC
The number of channels: 1 channel
Encoding date: 2021–08–23 11:28:03 UTC
Playback time: -
Application used: com.apple.VoiceMemos (Mac OS X 10.15.7)
Frame rate: 46.875 FPS (1024 SPF)
Codec type: Advanced Audio Codec Low Complexity (mp4a)
Metadata of multimedia container file:
Complete name: Media 3\MacbookPro 2.m4a
Format: MPEG-4
Format profile: Apple audio with iTunes info
Codec ID: M4A (M4A /isom/mp42)
File size: 409 KiB
Duration: 50 s 348 ms
Overall bit rate mode: Constant
Overall bit rate: 66.6 kb/s
Track name: Macbook Pro 2
Encoded date: UTC 2021–08–23 11:28:03
Tagged date: UTC 2021–08–23 11:28:54
Writing application: com.apple.VoiceMemos (Mac OS X 10.15.7)
voice-memo-uuid: 27013621–6644–45CB-8F7F-D4158479992B
Unique ID: 27013621–6644–45CB-8F7F-D4158479992B
More information can be seen below.
4. Below is the script (checkAudio.py) used to answer the fourth problem.
The result of ‘checkAudio.py’ script using option ‘d’ run on ‘E:\DF Korea Challenge\2021\308\bahan\Media 4’ is shown below.
The score I got for this problem is not perfect. This means that something might be missing or wrong. Let me know if you find something is missing or wrong. Feel free to leave any comments.
