lavc: use a separate field for exporting audio encoder padding

Currently, the amount of padding inserted at the beginning by some audio
encoders, is exported through AVCodecContext.delay. However
- the term 'delay' is heavily overloaded and can have multiple different
  meanings even in the case of audio encoding.
- this field has entirely different meanings, depending on whether the
  codec context is used for encoding or decoding (and has yet another
  different meaning for video), preventing generic handling of the codec
  context.

Therefore, add a new field -- AVCodecContext.initial_padding. It could
conceivably be used for decoding as well at a later point.

1 files changed, 2 insertions, 2 deletions

diff --git a/libavcodec/libopusenc.c b/libavcodec/libopusenc.c
index 9af8bcda7e..ee9655beef 100644
--- a/libavcodec/libopusenc.c
+++ b/libavcodec/libopusenc.c
@@ -87,7 +87,7 @@ static void libopus_write_header(AVCodecContext *avctx, int stream_count,
     bytestream_put_buffer(&p, "OpusHead", 8);
     bytestream_put_byte(&p, 1); /* Version */
     bytestream_put_byte(&p, channels);
-    bytestream_put_le16(&p, avctx->delay); /* Lookahead samples at 48kHz */
+    bytestream_put_le16(&p, avctx->initial_padding); /* Lookahead samples at 48kHz */
     bytestream_put_le32(&p, avctx->sample_rate); /* Original sample rate */
     bytestream_put_le16(&p, 0); /* Gain of 0dB is recommended. */
 
@@ -277,7 +277,7 @@ static int av_cold libopus_encode_init(AVCodecContext *avctx)
         goto fail;
     }
 
-    ret = opus_multistream_encoder_ctl(enc, OPUS_GET_LOOKAHEAD(&avctx->delay));
+    ret = opus_multistream_encoder_ctl(enc, OPUS_GET_LOOKAHEAD(&avctx->initial_padding));
     if (ret != OPUS_OK)
         av_log(avctx, AV_LOG_WARNING,
                "Unable to get number of lookahead samples: %s\n",