lavf: add AVFMT_FLAG_BITEXACT.

Use it instead of checking CODEC_FLAG_BITEXACT in the first stream's
codec context.

Using codec options inside lavf is fragile and can easily break when the
muxing codec context is not the encoding context.

1 files changed, 7 insertions, 0 deletions

diff --git a/libavformat/avformat.h b/libavformat/avformat.h
index 1ce3eba675..8d134a0945 100644
--- a/libavformat/avformat.h
+++ b/libavformat/avformat.h
@@ -1004,6 +1004,13 @@ typedef struct AVFormatContext {
 #define AVFMT_FLAG_CUSTOM_IO    0x0080 ///< The caller has supplied a custom AVIOContext, don't avio_close() it.
 #define AVFMT_FLAG_DISCARD_CORRUPT  0x0100 ///< Discard frames marked corrupted
 #define AVFMT_FLAG_FLUSH_PACKETS    0x0200 ///< Flush the AVIOContext every packet.
+/**
+ * When muxing, try to avoid writing any random/volatile data to the output.
+ * This includes any random IDs, real-time timestamps/dates, muxer version, etc.
+ *
+ * This flag is mainly intended for testing.
+ */
+#define AVFMT_FLAG_BITEXACT         0x0400
 
     /**
      * Maximum size of the data read from input for determining