commaai/openpilot · error · DataUnreadableError

Failed to index {fn!r}

Error message

Failed to index {fn!r}

What it means

get_index_data() requires a video index; if get_video_index(fn) returns None (no cached index and indexing produced nothing usable), it raises DataUnreadableError('Failed to index ...'). In practice get_video_index rarely returns None — assert_hvec/ffprobe usually raise earlier — so this is the catch-all when indexing silently yields nothing, e.g. via the cached path.

Source

Thrown at openpilot/tools/lib/framereader.py:87

def ffprobe(fn, fmt=None):
  fn = resolve_name(fn)
  cmd = ["ffprobe", "-v", "quiet", "-print_format", "json", "-show_format", "-show_streams"]
  if fmt:
    cmd += ["-f", fmt]
  cmd += ["-i", "pipe:0"]

  try:
    with FileReader(fn) as f:
      ffprobe_output = subprocess.check_output(cmd, input=f.read(4096))
  except subprocess.CalledProcessError as e:
    raise DataUnreadableError(fn) from e
  return json.loads(ffprobe_output)

def get_index_data(fn: str, index_data: dict|None = None):
  if index_data is None:
    index_data = get_video_index(fn)
    if index_data is None:
      raise DataUnreadableError(f"Failed to index {fn!r}")
  stream = index_data["probe"]["streams"][0]
  return index_data["index"], index_data["global_prefix"], stream["width"], stream["height"]

def get_video_index(fn):
  assert_hvec(fn)
  frame_types, dat_len, prefix = hevc_index(fn)
  index = np.array(frame_types + [(0xFFFFFFFF, dat_len)], dtype=np.uint32)
  probe = ffprobe(fn, "hevc")
  return {
    'index': index,
    'global_prefix': prefix,
    'probe': probe
  }

class FfmpegDecoder:
  def __init__(self, fn: str, index_data: dict|None = None,
               pix_fmt: str = "rgb24", hwaccel="auto", loglevel="quiet"):
    self.fn = fn

View on GitHub (pinned to 516ec1e682)

Solutions

1. Delete the framereader index cache for that route and retry so it is rebuilt
2. Validate the file directly: ffprobe and hevc_index on the same path to see which stage yields nothing
3. If it reproduces, the camera file itself is bad — re-download or use another segment

Example fix

# before
index, prefix, w, h = get_index_data(fn)

# after
from openpilot.tools.lib.framereader import get_index_data, DataUnreadableError
try:
    index, prefix, w, h = get_index_data(fn)
except DataUnreadableError:
    cache_clear_for(fn)  # or: os.remove(index_cache_path(fn))
    index, prefix, w, h = get_index_data(fn)

from openpilot.tools.lib.exceptions import DataUnreadableError
try:
    index, prefix, w, h = get_index_data(fn)
except DataUnreadableError:
    clear_framereader_cache(fn)
    index, prefix, w, h = get_index_data(fn)  # one rebuild attempt

When it happens

Trigger: Calling FrameReader/get_index_data on a file that passes the header check but produces no index — typically an index-cache miss combined with a degenerate stream, or when index_data passed in as None and the underlying file became unreadable between calls.

Common situations: Corrupted .idx/cache files produced by a previous partial run; race between concurrent processes writing the video index cache.

Related errors

• {fn} is empty
• {fn}
• Unsupported pixel format: {pix_fmt}
• invalid exponential-golomb code
• start index must be greater than zero

AI-assisted analysis of commaai/openpilot@516ec1e682 (2026-08-15). Data as JSON: /api/errors/993d3f980d4471ea. Report an issue: GitHub.