From a122c8038424a5e53ffea6fd7d50e46a0e918ca7 Mon Sep 17 00:00:00 2001
From: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Date: Thu, 10 Apr 2025 22:13:17 +0200
Subject: [PATCH 12/15] avcodec/mpegaudioenc: Avoid intermediate buffer
We know the final size before encoding, so we can switch to
ff_get_encode_buffer() which avoids an implicit memcpy().
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
---
libavcodec/mpegaudioenc.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/libavcodec/mpegaudioenc.c b/libavcodec/mpegaudioenc.c
index b10487b7ff..9a6aae6f78 100644
--- a/libavcodec/mpegaudioenc.c
+++ b/libavcodec/mpegaudioenc.c
@@ -508,7 +508,7 @@ static void psycho_acoustic_model(MpegAudioContext *s, short smr[SBLIMIT])
/* Try to maximize the smr while using a number of bits inferior to
the frame size. I tried to make the code simpler, faster and
smaller than other encoders :-) */
-static void compute_bit_allocation(MpegAudioContext *s,
+static unsigned compute_bit_allocation(MpegAudioContext *s,
short smr1[MPA_MAX_CHANNELS][SBLIMIT],
unsigned char bit_alloc[MPA_MAX_CHANNELS][SBLIMIT],
int *padding)
@@ -598,6 +598,7 @@ static void compute_bit_allocation(MpegAudioContext *s,
}
*padding = max_frame_size - current_frame_size;
av_assert0(*padding >= 0);
+ return max_frame_size / 8U;
}
/// Quantization & write sub band samples
@@ -740,6 +741,8 @@ static void encode_frame(MpegAudioContext *s,
encode_subbands(s, p, bit_alloc, 0);
#endif
+ av_assert1(put_bits_left(p) == padding);
+
/* padding */
for(i=0;i<padding;i++)
put_bits(p, 1, 0);
@@ -765,9 +768,10 @@ static int MPA_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
for(i=0;i<s->nb_channels;i++) {
psycho_acoustic_model(s, smr[i]);
}
- compute_bit_allocation(s, smr, bit_alloc, &padding);
+ unsigned frame_size = compute_bit_allocation(s, smr, bit_alloc, &padding);
- if ((ret = ff_alloc_packet(avctx, avpkt, MPA_MAX_CODED_FRAME_SIZE)) < 0)
+ ret = ff_get_encode_buffer(avctx, avpkt, frame_size, 0);
+ if (ret < 0)
return ret;
init_put_bits(&s->pb, avpkt->data, avpkt->size);
@@ -776,7 +780,6 @@ static int MPA_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
/* flush */
flush_put_bits(&s->pb);
- avpkt->size = put_bytes_output(&s->pb);
if (frame->pts != AV_NOPTS_VALUE)
avpkt->pts = frame->pts - ff_samples_to_time_base(avctx, avctx->initial_padding);
--
2.45.2