43 lines
1.8 KiB
C
43 lines
1.8 KiB
C
From 941fab9023f0af19f178771effd2a73865e849ba Mon Sep 17 00:00:00 2001
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From: ejurgensen <espenjurgensen@gmail.com>
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Date: Thu, 17 Aug 2023 23:09:41 +0200
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Subject: [PATCH] [xcode] Circumvent ffmpeg 6 ALAC encoding problem
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The default ffmpeg ALAC encoder, "alac", requires fixed frames of size 4096,
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but the Airplay 2 implementation feeds it with frames of size 352. Before
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ffmpeg 6 this worked, but not any more. Seems a frame size check has been
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added.
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This commit doesn't fix this, but circumvents the ffmpeg error by modifying the
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frame size that ffmpeg checks.
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Fixes issue #1640
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--- src/transcode.c.orig 2022-01-29 16:41:27 UTC
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+++ src/transcode.c
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@@ -42,6 +42,8 @@
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#include "misc.h"
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#include "transcode.h"
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+#define USE_ALAC_FRAME_SIZE_HACK (LIBAVCODEC_VERSION_MAJOR > 59) || ((LIBAVCODEC_VERSION_MAJOR == 59) && (LIBAVCODEC_VERSION_MINOR > 31))
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+
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// Interval between ICY metadata checks for streams, in seconds
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#define METADATA_ICY_INTERVAL 5
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// Maximum number of streams in a file that we will accept
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@@ -506,6 +508,16 @@ stream_add(struct encode_ctx *ctx, struct stream_ctx *
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avcodec_free_context(&s->codec);
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return -1;
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}
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+
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+ // airplay.c "misuses" the ffmpeg alac encoder in that it pushes frames with
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+ // 352 samples even though the encoder wants 4096 (and doesn't have variable
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+ // frame capability). This worked with no issues until ffmpeg 6, where it
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+ // seems a frame size check was added. The below circumvents the check, but is
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+ // dirty because we shouldn't be writing to this data element.
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+#if USE_ALAC_FRAME_SIZE_HACK
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+ if (codec_id == AV_CODEC_ID_ALAC)
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+ s->codec->frame_size = 352;
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+#endif
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// Copy the codec parameters we just set to the stream, so the muxer knows them
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ret = avcodec_parameters_from_context(s->stream->codecpar, s->codec);
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