The issue of Judge Arshad Malik’s video shown by Pakistan Muslim League-N (PML-N) Vice President and daughter of former prime minister, Maryam Nawaz Sharif, in a press conference has been much talked about these days.

The video is allegedly of a meeting between the judge and PML-N leader Nasir Butt. The judge tells in the video that he had sentenced former PM Nawaz Sharif to seven years in Al Azizia Mills reference under pressure last year.

Maryam Nawaz has claimed that she had a lot more to show to establish that the court verdict was driven by pressure.

This video has triggered a debate on media whether this video is counterfeit or genuine. On one hand the government leaders have termed it false and morphed, on the other hand, the PML-N leaders are stressing to get its forensic analysis to establish the truth.

Let’s see what forensic analysis of video is and if any kind of alteration and doctoring of a video could be caught through it.

How forensic analysis determines doctoring in a video?

Talking to BBC Urdu, a forensic media examiner James Zalik said forensic of a video can basically be divided into two parts, one is global and the other is local.

Global analysis can tell if the video has been altered or not but it cannot tell exactly where the tampering has been done. On the flip side, the local analysis can locate the exact location of contortion.

What procedure is used for analysis?

James Zalik said there were a number of software available for forensic analysis, however most of the times analysts use their self-made software. He said the experts used different types of analysis to pay close attention to different aspects of the video.

“Each video contains at least two streams one is pictorial and the other is sound. Firstly, video stream is examined. In this process video frames are checked separately. During its examination, it is tested if the flow of the stream has any difference or if a frame is missing,” he said.

Then, James Zalik said, sound streaming was checked. Its phases, energy, level of pressure and average of long-term spectrum were determined, he added.

“In the end, the folder in which the video file was present is analysed. The file’s structure, properties, EXIF data and header and footer of file are reviewed.

“Different results obtained after the complete analysis are matched to reach any conclusion in this regard,” he said.

Can forgery in video be caught through forensic analysis?

James Zalik said in the era of modern technology identifying a forgery was not out of question.

The question here arises is that whether any organization in Pakistan has the potential to discover if the video is genuine or there is suspicion of morphing or not?

The state-of-the-art forensic organization Punjab Forensic Science Agency (PFSA) has the machinery to analyse a video forensically but it could not be said with surety if it is latest technology from every aspect or not.

PFSA Additional Director General Muhammed Iqbal told BBC Urdu that his agency could conduct forensic analysis of a video, but it could not tell if the voice in the video was real or altered.

How is forensic analysis conducted in Pakistan?

Dr Iqbal said they conducted forensic analysis of video through examining it frame-by-frame. He said it could be done manually and with the help of software also. He said it was better if they had metadata of the video, otherwise they could still conduct the analysis through both the processes.

He said the third process was to overlap frames of the video to judge its authenticity.

No facility available for analysis of voice

The PSCA additional director general said they did not have the facility to conduct analysis of voice. He said the institution did not have the software to find voice forgery for it was much too expensive and they received very few such requests.

How is voice forgery identified in a video?

James Zalik said first of all you have to see if the voice matched the video. He said streaming of voice was also checked, whether its frequency, bandwidth, pressure limits and codec matched or not.

He said even after altering a video its traces were left to be detected.

“There are so many software available to judge authenticity of a video but they are not known to common men and neither everybody can understand them. Therefore, it is impossible that the doctoring go unnoticed,” he said.