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• avcodec/vvcdec : inter, wait reference with a different resolution

  19 mai 2024, par Nuo Mi

  avcodec/vvcdec : inter, wait reference with a different resolution
  For RPR, the current frame may reference a frame with a different resolution.
  
  Therefore, we need to consider frame scaling when we wait for reference pixels.
  

  • [DH] libavcodec/vvc/dec.c
  • [DH] libavcodec/vvc/dec.h
  • [DH] libavcodec/vvc/refs.c
  • [DH] libavcodec/vvc/thread.c

• How to change resolution without compromising video quality using ffmpeg ?

  20 mars 2024, par blake banker

  I'm trying to develop a simple video transcoding system.
When you upload a video,
After extracting the video and audio separately,
I want to encode them at 360, 720, and 1080p resolutions respectively and then merge them to create three final mp4 files.
At this time, I have two questions.

  


  


  1. Is there a big difference between encoding the video and audio separately in the original video file and encoding the original video file as is ? In a related book, it is said that a system is created by separating video and audio, and I am curious as to why.

     


  


  2. I want to change the resolution without compromising the original image quality. At this time, the resolution of the uploaded file can be known at the time of upload. As a test, I created files according to each resolution, and found that the image quality was damaged. If I want to change only the resolution while keeping the original image quality, I would like to know how to adjust each ffmpeg option. We plan to change it to 360, 720, and 1080p.

     


  


  


• Setting up multiple resolution value in Fast API for transcoding uploaded video files

  23 janvier 2024, par Sanji Vinsmoke

  I created an API for transcoding video files like adaptive bit rate of youtube. I used Fast API. Currently, I am trying to set resolution values for each file. But whenever I am adding multiple resolutions, I am recieving "422 unprocessible entity" error in the Swagger.

  


  Here is my code :

  


  async def transcode_video(input_path, output_folder, res, unique_id, total_files, pbar):
 # Use asyncio for command execution with progress bar
 output_path = os.path.join(output_folder, f"{res}p.m3u8")

 # Calculate the target size
 target_size = calculate_target_size(input_path)

 cmd_duration = f"ffprobe -v error -show_entries format=duration -of default=noprint_wrappers=1:nokey=1 {input_path}"
 total_duration = float(subprocess.check_output(cmd_duration, shell=True, text=True).strip())

 cmd = (
     f"ffmpeg -i {input_path} -vf scale=-2:{res} -c:a aac -b:a 128k "
     f"-g 50 -hls_time 1 -hls_list_size 0 "
     f"-crf 23 -b:v 100k -fs {target_size} "
     f"-hls_segment_filename \"{output_path.replace('.m3u8', '_%03d.ts')}\" "
     f"{output_path}"
 )

 process = await asyncio.create_subprocess_shell(
     cmd,
     stdout=asyncio.subprocess.PIPE,
     stderr=asyncio.subprocess.PIPE
 )

 while True:
     line = await process.stderr.readline()
     if not line:
         break
     line = line.decode().strip()
     if "time=" in line:
         # Extracting the time progress from FFmpeg output
         time_str = line.split("time=")[1].split()[0]
         current_time = sum(x * float(t) for x, t in zip([3600, 60, 1], time_str.split(":")))
         progress = (current_time / total_duration) * 100
         pbar.update(progress - pbar.n)

 # Wait for the transcoding process to complete
 await process.wait()

 if process.returncode != 0:
     raise HTTPException(status_code=500, detail="Video transcoding failed.")
 pbar.close()

 # Increment the total number of transcoded files
 total_files[0] += 1

@app.post("/transcode/")
async def transcode_video_endpoint(files: List[UploadFile] = File(...), resolutions: List[int] = None):
 # Counters for transcoded videos
 total_files = [0]

 # Iterate over each file
 for file in files:
     # Check if the file is a valid video file based on its extension
     valid_video_extensions = {".mp4", ".avi", ".mkv", ".mov", ".wmv", ".flv"}
     if not any(file.filename.lower().endswith(ext) for ext in valid_video_extensions):
         print(f"Skipping non-video file: {file.filename}")
         continue

     # Assign a unique ID for each file
     unique_id = str(uuid.uuid4())

     # Log the filename and unique ID
     print(f"Processing file: {file.filename} with unique ID: {unique_id}")

     # Create a folder for the unique ID
     unique_id_folder = os.path.join(OUTPUT_FOLDER, unique_id)
     Path(unique_id_folder).mkdir(parents=True, exist_ok=True)

     # Save the uploaded file
     input_path = os.path.join(UPLOAD_FOLDER, file.filename)
     with open(input_path, "wb") as video_file:
         video_file.write(file.file.read())

     # Check if the file is a valid video file using ffprobe
     try:
         subprocess.run(
             ["ffprobe", "-v", "error", "-select_streams", "v:0", "-show_entries", "stream=codec_type", "-of", "csv=p=0", input_path],
             check=True, capture_output=True
         )
     except subprocess.CalledProcessError:
         print(f"Skipping non-video file: {file.filename}")
         continue

     # Determine the resolutions to transcode based on the provided or default resolution
     resolutions_to_transcode = [res for res in [240, 360, 480, 720] if resolutions is None or res in resolutions]

     # If resolutions is not exactly 360, 480, 720, or 1080, transcode to the nearest lower resolution
     if resolutions is not None:
         resolutions_to_transcode = [get_closest_lower_resolution(res) for res in resolutions]

     # Transcode the video into the specified resolutions
     for res in resolutions_to_transcode:
         output_folder = os.path.join(unique_id_folder, f"{res}p")
         Path(output_folder).mkdir(parents=True, exist_ok=True)

         # Call the transcode_video function with tqdm progress bar
         with tqdm(total=100, desc=f"Transcoding {res}p", position=0, leave=True) as pbar:
             await transcode_video(input_path, output_folder, res, unique_id, total_files, pbar)

     # Create index.m3u8 file after transcoding all resolutions
     create_index_m3u8(unique_id, resolutions_to_transcode)

 return JSONResponse(content={"message": f"{total_files[0]} videos transcoded."})


  


  If I provide one resolution it works fine. But if I provide a list of resolutions for all the uploaded videos I am getting error 422.

  


  
Code    Details
422 
Error: Unprocessable Entity

Response body
Download
{
  "detail": [
    {
      "loc": [
        "body",
        "resolutions",
        0
      ],
      "msg": "value is not a valid integer",
      "type": "type_error.integer"
    }
  ]
}


  


  I used python 3.8.18. Can you help me please ? I tried with list, object but always getting the error.