如何使用ffmpeg从解密后的RTP流中提取H.264数据？

Absolutely! FFmpeg is fully capable of pulling raw H.264 content from a decrypted RTP stream—this is a routine task for anyone working with media streaming. Let’s break down exactly how to do it, covering both real-time streams and pre-saved RTP files.

Basic Command for Real-Time Decrypted RTP Streams #

If you’re receiving a live decrypted RTP stream over UDP, use this command:

ffmpeg -i rtp://<your-ip>:<your-port> -c:v copy -f h264 extracted_h264.h264

Let’s unpack each part:

• rtp://<your-ip>:<your-port>: Replace <your-ip> and <your-port> with the actual IP address and port where the decrypted RTP stream is being sent.
• -c:v copy: This tells FFmpeg to copy the video stream directly without re-encoding it. This preserves the original H.264 quality and is much faster than transcoding.
• -f h264: Forces FFmpeg to output a raw H.264 elementary stream (not wrapped in a container like MP4 or MKV).
• extracted_h264.h264: The name of your output file—feel free to rename this to something more descriptive.

For Pre-Saved Decrypted RTP Files #

If you already have a file containing decrypted RTP packets (e.g., input.rtp), the command is almost identical:

ffmpeg -i input.rtp -c:v copy -f h264 extracted_h264.h264

Troubleshooting Tips #

• Dynamic Payload Type Issues: If your H.264 stream uses a dynamic payload type (common for custom setups, often 96), you may need to explicitly specify it in the input URL:

  ffmpeg -i rtp://<your-ip>:<your-port>?payload_type=96 -c:v copy -f h264 extracted_h264.h264
  

• Verify the Output: To make sure your extracted H.264 is valid, use FFplay to test it:

  ffplay extracted_h264.h264
  

• Missing SPS/PPS: In rare cases, if the RTP stream doesn’t include SPS/PPS headers (required for H.264 playback), you may need to manually inject them. But most decrypted H.264-over-RTP streams include these by default.

内容的提问来源于stack exchange，提问作者Brad Reiter