How to Remove Extra PCR Timestamps from MPG File Using FFmpeg

Learn how to remove extra PCR timestamps from an MPG file using FFmpeg, a powerful command-line tool for video processing.

If you have an MPG file that contains extra PCR timestamps, you may encounter some problems when playing or editing it. For example, the video may stutter, freeze, or have incorrect duration. In this article, we will show you how to remove extra PCR timestamps from an MPG file using FFmpeg, a powerful command-line tool for video processing. We will also explain what PCR timestamps are, why they are important, and how they can cause issues in some cases.

What are PCR Timestamps?

PCR stands for Program Clock Reference, and it is a special type of timestamp that is used in MPEG transport streams (TS) to synchronize the audio and video streams. A PCR timestamp indicates the exact time when a packet should be decoded and presented to the user. PCR timestamps are essential for maintaining the continuity and quality of the playback.

Why Do Some MPG Files Have Extra PCR Timestamps?

An MPG file is a container format that can store multiple streams of data, such as audio, video, subtitles, and metadata. An MPG file can also store an MPEG transport stream (TS) as one of its streams. A TS is a packet-based format that is commonly used for broadcasting and streaming purposes. A TS can have multiple programs, each with its own PCR timestamp.

However, some MPG files may have extra PCR timestamps that are not associated with any program. These extra PCR timestamps may be inserted by some devices or software that capture or process the TS. For example, some digital TV tuners may add extra PCR timestamps to the TS to improve the reception quality. Some video editing software may also add extra PCR timestamps to the TS to facilitate the editing process.

How Do Extra PCR Timestamps Affect the MPG File?

Extra PCR timestamps can cause some problems when playing or editing an MPG file. For example:

• Some video players may get confused by the extra PCR timestamps and display the wrong duration or position of the video. They may also skip or repeat some frames or segments of the video.
• Some video editors may not be able to handle the extra PCR timestamps and fail to import or export the video correctly. They may also produce corrupted or distorted output files.
• Some video converters may not be able to recognize the extra PCR timestamps and generate errors or warnings. They may also produce output files with incorrect parameters or quality.

How to Remove Extra PCR Timestamps from an MPG File Using FFmpeg?

FFmpeg is a powerful command-line tool that can perform various operations on video and audio files, such as encoding, decoding, filtering, muxing, demuxing, and more. FFmpeg can also remove extra PCR timestamps from an MPG file using the -fix_sub_duration option. This option instructs FFmpeg to discard any PCR timestamp that does not belong to a program.

To remove extra PCR timestamps from an MPG file using FFmpeg, you can use the following command:

ffmpeg -i input.mpg -fix_sub_duration -c copy output.mpg

This command will copy the input file to the output file without re-encoding, and remove any extra PCR timestamps along the way. The -c copy option tells FFmpeg to copy the streams without changing their codecs or parameters. The -fix_sub_duration option tells FFmpeg to fix the duration of the sub-streams based on the PCR timestamps.

You can also use the -map option to select which streams you want to copy to the output file. For example, if you only want to copy the video stream and discard the audio and subtitle streams, you can use the following command:

ffmpeg -i input.mpg -fix_sub_duration -map 0:v -c copy output.mpg

The -map 0:v option tells FFmpeg to map the video stream from the first input file (0) to the output file.

Frequently Asked Questions (FAQs)

Question: How can I check if my MPG file has extra PCR timestamps?

Answer: You can use the ffprobe tool that comes with FFmpeg to inspect the PCR timestamps of your MPG file. For example, you can use the following command to show the PCR timestamps of each packet:

ffprobe -show_packets -show_entries packet=pts_time,pcr -of csv input.mpg

This command will output a CSV file with the presentation timestamp (PTS) and the PCR of each packet. You can then look for any PCR that does not match the PTS of the corresponding packet.

Question: How can I preserve the original timestamps of the MPG file when removing extra PCR timestamps?

Answer: You can use the -copyts option to tell FFmpeg to copy the original timestamps of the input file to the output file. For example, you can use the following command to preserve the original timestamps:

ffmpeg -i input.mpg -fix_sub_duration -copyts -c copy output.mpg

This command will copy the original timestamps of the input file to the output file, and remove any extra PCR timestamps along the way.

Qustion: How can I remove extra PCR timestamps from other video formats, such as MKV or MP4?

Answer: You can use the same method as described above, but you need to change the output file extension to match the desired format. For example, if you want to remove extra PCR timestamps from an MKV file, you can use the following command:

ffmpeg -i input.mkv -fix_sub_duration -c copy output.mkv

This command will copy the input file to the output file without re-encoding, and remove any extra PCR timestamps along the way.

Summary

In this article, we have learned how to remove extra PCR timestamps from an MPG file using FFmpeg, a powerful command-line tool for video processing. We have also explained what PCR timestamps are, why they are important, and how they can cause issues in some cases. We have also shown how to check if your MPG file has extra PCR timestamps, how to preserve the original timestamps of the MPG file, and how to remove extra PCR timestamps from other video formats.

Disclaimer: This article is for informational purposes only and does not constitute professional advice. The author and the publisher are not liable for any damages or losses that may result from the use of the information or tools in this article. The user is responsible for verifying the accuracy and suitability of the information and tools before using them. The user should also backup their files before performing any operation on them.