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# type: ignore
"""
FFmpeg has a logging system that it uses extensively. It's very noisy, so PyAV turns it
off by default. This unfortunately has the effect of making raised errors have less
detailed messages. It's therefore recommended to use VERBOSE when developing.
.. _enable_logging:
Enabling Logging
~~~~~~~~~~~~~~~~~
You can hook into the logging system with Python by setting the log level::
import av
av.logging.set_level(av.logging.VERBOSE)
PyAV hooks into that system to translate FFmpeg logs into Python's
`logging system <https://docs.python.org/3/library/logging.html#logging.basicConfig>`_.
If you are not already using Python's logging system, you can initialize it
quickly with::
import logging
logging.basicConfig()
Note that handling logs with Python sometimes doesn't play nicely with multi-threaded workflows.
An alternative is :func:`restore_default_callback`.
This restores FFmpeg's default logging system, which prints to the terminal.
Like with setting the log level to ``None``, this may also result in raised errors
having less detailed messages.
API Reference
~~~~~~~~~~~~~
"""
import logging
import sys
from threading import Lock, get_ident
import cython
from cython.cimports.libc.stdio import fprintf, stderr
from cython.cimports.libc.stdlib import free, malloc
# Library levels.
PANIC = lib.AV_LOG_PANIC # 0
FATAL = lib.AV_LOG_FATAL # 8
ERROR = lib.AV_LOG_ERROR
WARNING = lib.AV_LOG_WARNING
INFO = lib.AV_LOG_INFO
VERBOSE = lib.AV_LOG_VERBOSE
DEBUG = lib.AV_LOG_DEBUG
TRACE = lib.AV_LOG_TRACE
# Mimicking stdlib.
CRITICAL = FATAL
@cython.ccall
def adapt_level(level: cython.int):
"""Convert a library log level to a Python log level."""
if level <= lib.AV_LOG_FATAL: # Includes PANIC
return 50 # logging.CRITICAL
elif level <= lib.AV_LOG_ERROR:
return 40 # logging.ERROR
elif level <= lib.AV_LOG_WARNING:
return 30 # logging.WARNING
elif level <= lib.AV_LOG_INFO:
return 20 # logging.INFO
elif level <= lib.AV_LOG_VERBOSE:
return 10 # logging.DEBUG
elif level <= lib.AV_LOG_DEBUG:
return 5 # Lower than any logging constant.
else: # lib.AV_LOG_TRACE
return 1
level_threshold = cython.declare(object, None)
# ... but lets limit ourselves to WARNING (assuming nobody already did this).
if "libav" not in logging.Logger.manager.loggerDict:
logging.getLogger("libav").setLevel(logging.WARNING)
def get_level():
"""Returns the current log level. See :func:`set_level`."""
return level_threshold
def set_level(level):
"""set_level(level)
Sets PyAV's log level. It can be set to constants available in this
module: ``PANIC``, ``FATAL``, ``ERROR``, ``WARNING``, ``INFO``,
``VERBOSE``, ``DEBUG``, or ``None`` (the default).
PyAV defaults to totally ignoring all ffmpeg logs. This has the side effect of
making certain Exceptions have no messages. It's therefore recommended to use:
av.logging.set_level(av.logging.VERBOSE)
When developing your application.
"""
global level_threshold
if level is None:
level_threshold = level
lib.av_log_set_callback(nolog_callback)
elif type(level) is int:
level_threshold = level
lib.av_log_set_callback(log_callback)
else:
raise ValueError("level must be: int | None")
def set_libav_level(level):
"""Set libav's log level. It can be set to constants available in this
module: ``PANIC``, ``FATAL``, ``ERROR``, ``WARNING``, ``INFO``,
``VERBOSE``, ``DEBUG``.
When PyAV logging is disabled, setting this will change the level of
the logs printed to the terminal.
"""
lib.av_log_set_level(level)
def restore_default_callback():
"""Revert back to FFmpeg's log callback, which prints to the terminal."""
lib.av_log_set_callback(lib.av_log_default_callback)
skip_repeated = cython.declare(cython.bint, True)
skip_lock = cython.declare(object, Lock())
last_log = cython.declare(object, None)
skip_count = cython.declare(cython.int, 0)
def get_skip_repeated():
"""Will identical logs be emitted?"""
return skip_repeated
def set_skip_repeated(v):
"""Set if identical logs will be emitted"""
global skip_repeated
skip_repeated = bool(v)
# For error reporting.
last_error = cython.declare(object, None)
error_count = cython.declare(cython.int, 0)
@cython.ccall
def get_last_error():
"""Get the last log that was at least ``ERROR``."""
if error_count:
with skip_lock:
return error_count, last_error
else:
return 0, None
global_captures = cython.declare(list, [])
thread_captures = cython.declare(dict, {})
@cython.cclass
class Capture:
"""A context manager for capturing logs.
:param bool local: Should logs from all threads be captured, or just one
this object is constructed in?
e.g.::
with Capture() as logs:
# Do something.
for log in logs:
print(log.message)
"""
logs = cython.declare(list, visibility="readonly")
captures = cython.declare(list, visibility="private")
def __init__(self, local: cython.bint = True):
self.logs = []
if local:
self.captures = thread_captures.setdefault(get_ident(), [])
else:
self.captures = global_captures
def __enter__(self):
self.captures.append(self.logs)
return self.logs
def __exit__(self, type_, value, traceback):
self.captures.pop()
log_context = cython.struct(
class_=cython.pointer[lib.AVClass],
name=cython.p_char,
)
item_name_func = cython.typedef("const char *(*item_name_func)(void *) noexcept nogil")
@cython.cfunc
@cython.nogil
@cython.exceptval(check=False)
def log_context_name(ptr: cython.p_void) -> cython.p_char:
obj: cython.pointer[log_context] = cython.cast(cython.pointer[log_context], ptr)
return obj.name
log_class = cython.declare(lib.AVClass)
log_class.item_name = cython.cast(item_name_func, log_context_name)
@cython.ccall
def log(level: cython.int, name: str, message: str):
"""Send a log through the library logging system.
This is mostly for testing.
"""
obj: cython.pointer[log_context] = cython.cast(
cython.pointer[log_context], malloc(cython.sizeof(log_context))
)
obj.class_ = cython.address(log_class)
obj.name = name
message_bytes: bytes = message.encode("utf-8")
lib.av_log(
cython.cast(cython.p_void, obj),
level,
"%s",
cython.cast(cython.p_char, message_bytes),
)
free(obj)
@cython.cfunc
def log_callback_gil(
level: cython.int, c_name: cython.p_const_char, c_message: cython.p_char
):
global error_count
global skip_count
global last_log
global last_error
name = cython.cast(str, c_name) if c_name is not cython.NULL else ""
message = cython.cast(bytes, c_message).decode("utf8", "backslashreplace")
log = (level, name, message)
# We have to filter it ourselves, but we will still process it in general so
# it is available to our error handling.
# Note that FFmpeg's levels are backwards from Python's.
is_interesting: cython.bint = level <= level_threshold
# Skip messages which are identical to the previous.
# TODO: Be smarter about threads.
is_repeated: cython.bint = False
repeat_log: object = None
with skip_lock:
if is_interesting:
is_repeated = skip_repeated and last_log == log
if is_repeated:
skip_count += 1
elif skip_count:
# Now that we have hit the end of the repeat cycle, tally up how many.
if skip_count == 1:
repeat_log = last_log
else:
repeat_log = (
last_log[0],
last_log[1],
"%s (repeated %d more times)" % (last_log[2], skip_count),
)
skip_count = 0
last_log = log
# Hold onto errors for err_check.
if level == lib.AV_LOG_ERROR:
error_count += 1
last_error = log
if repeat_log is not None:
log_callback_emit(repeat_log)
if is_interesting and not is_repeated:
log_callback_emit(log)
@cython.cfunc
def log_callback_emit(log):
lib_level, name, message = log
captures = thread_captures.get(get_ident()) or global_captures
if captures:
captures[-1].append(log)
return
py_level = adapt_level(lib_level)
logger_name = "libav." + name if name else "libav.generic"
logger = logging.getLogger(logger_name)
logger.log(py_level, message.strip())
@cython.cfunc
@cython.nogil
@cython.exceptval(check=False)
def log_callback(
ptr: cython.p_void,
level: cython.int,
format: cython.p_const_char,
args: lib.va_list,
) -> cython.void:
inited: cython.bint = Py_IsInitialized()
if not inited:
return
with cython.gil:
if level > level_threshold and level != lib.AV_LOG_ERROR:
return
# Format the message.
message: cython.char[1024]
vsnprintf(message, 1023, format, args)
# Get the name.
name: cython.p_const_char = cython.NULL
cls: cython.pointer[lib.AVClass] = (
cython.cast(cython.pointer[cython.pointer[lib.AVClass]], ptr)[0]
if ptr
else cython.NULL
)
if cls and cls.item_name:
name = cls.item_name(ptr)
with cython.gil:
try:
log_callback_gil(level, name, message)
except Exception:
fprintf(
stderr,
"av.logging: exception while handling %s[%d]: %s\n",
name,
level,
message,
)
# For some reason PyErr_PrintEx(0) won't work.
exc, type_, tb = sys.exc_info()
PyErr_Display(exc, type_, tb)
@cython.cfunc
@cython.nogil
@cython.exceptval(check=False)
def nolog_callback(
ptr: cython.p_void,
level: cython.int,
format: cython.p_const_char,
args: lib.va_list,
) -> cython.void:
pass
lib.av_log_set_callback(nolog_callback)

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