Convert an h264 byte string to OpenCV images

Question

In Python, how do I convert an h264 byte string to images OpenCV can read, only keeping the latest image?

Long version:

Hi everyone.

Working in Pytho

Answer 1

Use any of these:

ffmpeg -i - -pix_fmt bgr24 -f rawvideo -
ffmpeg -i pipe: -pix_fmt bgr24 -f rawvideo pipe:
ffmpeg -i pipe:0 -pix_fmt bgr24 -f rawvideo pipe:1

• You didn't provide much info about your input so you may need to add additional input options.

• You didn't specify your desired output format so I just chose rawvideo. You can see a list of supported output formats (muxers) with ffmpeg -muxers (or ffmpeg -formats if your ffmpeg is outdated). Not all are suitable for piping, such as MP4.

• See FFmpeg Protocols: pipe.

Answer 2

It works well just a minor changes: This will read the stream in a loop and show each time the last image

adbCmd = ['adb', 'exec-out', 'screenrecord', '--output-format=h264', '-']
stream = sp.Popen(adbCmd, stdout = sp.PIPE)

ffmpegCmd =['ffmpeg', '-i', '-', '-f', 'rawvideo', '-vf', 'scale=324:576', 
'-vcodec', 'bmp',  '-']
ffmpeg = sp.Popen(ffmpegCmd, stdin = stream.stdout, stdout = sp.PIPE)

while True:
    fileSizeBytes = ffmpeg.stdout.read(6)
    fileSize = 0
    for i in xrange(4):
        fileSize += array.array('B',fileSizeBytes[i + 2])[0] * 256 ** i
    bmpData = fileSizeBytes + ffmpeg.stdout.read(fileSize - 6)
    image = cv2.imdecode(np.fromstring(bmpData, dtype = np.uint8), 1)
    cv2.imshow("im",image) 
    cv2.waitKey(25)