def __get_streaming_video_download_cmd(self):
# --retries infinite: in case downloading has transient errors
youtube_dl_cmd_template = "yt-dlp {0} --retries infinite --format {1} --output - {2} | {3}"
log_opts = '--no-progress'
if Logger.get_level() <= Logger.DEBUG:
log_opts = '' # show video download progress
if not sys.stderr.isatty():
log_opts += ' --newline'
# 50 MB. Based on one video, 1080p avc1 video consumes about 0.36 MB/s. So this should
# be enough buffer for ~139s for a 1080p video, which is a lot higher resolution than we
# are ever likely to use.
video_buffer_size = 1024 * 1024 * 50
# Choose 'worst' video because we want our pixel ffmpeg video scaler to do less work when we
# scale the video down to the LED matrix size.
#
# But the height should be at least the height of the LED matrix (this probably only matters
# if someone made a very large LED matrix such that the worst quality video was lower resolution
# than the LED matrix pixel dimensions). Filter on only height so that vertical videos don't
# result in a super large resolution being chosen? /shrug ... could consider adding a filter on
# width too.
#
# Use avc1 because this means h264, and the pi has hardware acceleration for this format.
# See: https://github.com/dasl-/piwall2/blob/88030a47790e5ae208d2c9fe19f9c623fc736c83/docs/video_formats_and_hardware_acceleration.adoc#youtube--youtube-dl
#
# Fallback onto 'worst' rather than 'worstvideo', because some videos (live videos) only
# have combined video + audio formats. Thus, 'worstvideo' would fail for them.
video_format = (
f'worstvideo[vcodec^=avc1][height>={Config.get_or_throw("leds.display_height")}]/'
+
f'worst[vcodec^=avc1][height>={Config.get_or_throw("leds.display_height")}]'
)
youtube_dl_video_cmd = youtube_dl_cmd_template.format(
shlex.quote(self.__url), shlex.quote(video_format), log_opts,
self.__get_mbuffer_cmd(video_buffer_size))
# Also use a 50MB buffer, because in some cases, the audio stream we download may also contain video.
audio_buffer_size = 1024 * 1024 * 50
youtube_dl_audio_cmd = youtube_dl_cmd_template.format(
shlex.quote(self.__url),
# bestaudio: try to select the best audio-only format
# bestaudio*: this is the fallback option -- select the best quality format that contains audio.
# It may also contain video, e.g. in the case that there are no audio-only formats available.
# Some videos (live videos) only have combined video + audio formats. Thus 'bestaudio' would
# fail for them.
shlex.quote('bestaudio/bestaudio*'),
log_opts,
self.__get_mbuffer_cmd(audio_buffer_size))
# Mux video from the first input with audio from the second input: https://stackoverflow.com/a/12943003/627663
# We need to specify, because in some cases, either input could contain both audio and video. But in most
# cases, the first input will have only video, and the second input will have only audio.
return (
f"{self.get_standard_ffmpeg_cmd()} -i <({youtube_dl_video_cmd}) -i <({youtube_dl_audio_cmd}) "
+ "-c copy -map 0:v:0 -map 1:a:0 -shortest -f mpegts -")
def get_standard_ffmpeg_cmd():
# unfortunately there's no way to make ffmpeg output its stats progress stuff with line breaks
log_opts = '-nostats '
if sys.stderr.isatty():
log_opts = '-stats '
if Logger.get_level() <= Logger.DEBUG:
pass # don't change anything, ffmpeg is pretty verbose by default
else:
log_opts += '-loglevel error'
# Note: don't use ffmpeg's `-xerror` flag:
# https://gist.github.com/dasl-/1ad012f55f33f14b44393960f66c6b00
return f"ffmpeg -hide_banner {log_opts} "