lavf: switch to AVStream.time_base as the hint for the muxer timebase

Previously, AVStream.codec.time_base was used for that purpose, which
was quite confusing for the callers. This change also opens the path for
removing AVStream.codec.

The change in the lavf-mkv test is due to the native timebase (1/1000)
being used instead of the default one (1/90000), so the packets are now
sent to the crc muxer in the same order in which they are demuxed
(previously some of them got reordered because of inexact timestamp
conversion).

1 files changed, 6 insertions, 3 deletions

diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index b17c791eac..473b8daedf 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -710,9 +710,12 @@ typedef struct AVStream {
      * of which frame timestamps are represented.
      *
      * decoding: set by libavformat
-     * encoding: set by libavformat in avformat_write_header. The muxer may use the
-     * user-provided value of @ref AVCodecContext.time_base "codec->time_base"
-     * as a hint.
+     * encoding: May be set by the caller before avformat_write_header() to
+     *           provide a hint to the muxer about the desired timebase. In
+     *           avformat_write_header(), the muxer will overwrite this field
+     *           with the timebase that will actually be used for the timestamps
+     *           written into the file (which may or may not be related to the
+     *           user-provided one, depending on the format).
      */
     AVRational time_base;