Read number of frames

README.md

To install it:

pip install -r requirements.txt

To execute it:

python read_video.py path/to/video.mp4

Note: Depending on your python configuration you may need to call it pip3 and python3. Note2: The function will return fps, frame, pts, and "timestamps".

read_video.py

import av
import numpy as np
import logging

from rich.progress import Progress

logging.basicConfig(
    format="%(asctime)s - %(levelname)s - %(message)s", level=logging.INFO
)


def read_video_ts(video_path, audio=False, auto_thread_type=True):
    """
    A function to read a video and return the fps,
    the number of frames, the pts and timestamps.
    :param video_path: the path to the video
    """
    nframes = []
    # Read the video
    with av.open(video_path) as video_container:
        if audio:
            stream = video_container.streams.audio[0]
        else:
            stream = video_container.streams.video[0]
        if auto_thread_type:
            stream.thread_type = "AUTO"
        fps = stream.average_rate  # alt base_rate or guessed_rate
        nframes = stream.frames
        logging.info("Extracting pts...")
        pts, dts, ts = (list() for i in range(3))
        with Progress() as progress:
            decode_task = progress.add_task("👓 Decoding...", total=nframes)
            for packet in video_container.demux(stream):
                for frame in packet.decode():
                    if frame is not None and frame.pts is not None:
                        pts.append(frame.pts)
                        dts.append(
                            frame.dts
                        ) if frame.dts is not None else logging.info(
                            f"Decoding timestamp is missing at frame {len(pts)}"
                        )
                        ts.append(
                            (
                                frame.pts * frame.time_base
                                - stream.start_time * frame.time_base
                            )
                            * 1e9
                        )
                progress.advance(decode_task)
            progress.stop_task(decode_task)
        pts, dts, ts = (
            np.array(pts, dtype=np.uint64),
            np.array(dts, dtype=np.uint64),
            np.array(ts, dtype=np.uint64),
        )
        if not isMonotonicInc(pts):
            logging.warning("Pts are not monotonic increasing!.")
        if np.array_equal(pts, dts):
            logging.info("Pts and dts are equal, using pts")

        idc = pts.argsort()
        pts = pts[idc]
        ts = ts[idc]

        if nframes != len(pts):
            nframes = len(pts)
        else:
            logging.info(f"This video has {nframes} frames")
    return fps, nframes, pts, ts


def isMonotonicInc(a2check):
    return all(a2check[i] <= a2check[i + 1] for i in range(len(a2check) - 1))


if __name__ == "__main__":
    import sys

    read_video_ts(sys.argv[1])

requirements.txt

rich
numpy
av