segy: nice error message when trying to write a trace with too many

samples

CHANGELOG.txt

@@ -58,6 +58,9 @@ master:
      16/32bit integers, see #2058 and #2059)
  - obspy.io.rg16:
    * implement module to read waveforms and headers from fcnt format (see #2265).
+ - obspy.io.segy:
+   * show nice error message when trying to write a trace with too many samples
+     in it (see #2358, #1393)
  - obspy.io.quakeml:
    * Allow writing invalid ids but raise a warning
      (see #2104, #2090, #2093, #1872).

obspy/io/segy/core.py

@@ -20,6 +20,7 @@
 
 from obspy import Stream, Trace, UTCDateTime
 from obspy.core import AttribDict
+from obspy.core.util.obspy_types import ObsPyException
 from .header import (BINARY_FILE_HEADER_FORMAT, DATA_SAMPLE_FORMAT_CODE_DTYPE,
                      ENDIAN, TRACE_HEADER_FORMAT, TRACE_HEADER_KEYS)
 from .segy import _read_segy as _read_segyrev1
@@ -37,6 +38,8 @@
 # of the SEG Y format.
 MAX_INTERVAL_IN_SECONDS = 0.065535
 
+# largest number possible with int16
+MAX_NUMBER_OF_SAMPLES = 32767
 
 class SEGYCoreWritingError(SEGYError):
     """
@@ -270,6 +273,12 @@ def _write_segy(stream, filename, data_encoding=None, byteorder=None,
     the SEG Y format. Therefore the smallest possible sampling rate is ~ 15.26
     Hz. Please keep that in mind.
     """
+    for i, tr in enumerate(stream):
+        if len(tr) > MAX_NUMBER_OF_SAMPLES:
+            msg = ('Can not write traces with more than {:d} samples (trace '
+                    'at index {:d}):\n{!s}')
+            raise ObsPyException(msg.format(MAX_NUMBER_OF_SAMPLES, i, tr))
+
     # Some sanity checks to catch invalid arguments/keyword arguments.
     if data_encoding is not None and data_encoding not in VALID_FORMATS:
         msg = "Invalid data encoding."