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Code Issues Releases Activity

avcodec/mpegaudioenc: Avoid intermediate buffer

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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>
This commit is contained in:
Andreas Rheinhardt
2025-04-10 22:13:17 +02:00
parent 6f7ebeff70
commit 87f3e20931
1 changed files with 7 additions and 4 deletions
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11
libavcodec/mpegaudioenc.c
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@ -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 /* 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 the frame size. I tried to make the code simpler, faster and
smaller than other encoders :-) */ smaller than other encoders :-) */
static void compute_bit_allocation(MpegAudioContext *s, static unsigned compute_bit_allocation(MpegAudioContext *s,
short smr1[MPA_MAX_CHANNELS][SBLIMIT], short smr1[MPA_MAX_CHANNELS][SBLIMIT],
unsigned char bit_alloc[MPA_MAX_CHANNELS][SBLIMIT], unsigned char bit_alloc[MPA_MAX_CHANNELS][SBLIMIT],
int *padding) int *padding)
@ -598,6 +598,7 @@ static void compute_bit_allocation(MpegAudioContext *s,
} }
*padding = max_frame_size - current_frame_size; *padding = max_frame_size - current_frame_size;
av_assert0(*padding >= 0); av_assert0(*padding >= 0);
return max_frame_size / 8U;
} }
/// Quantization & write sub band samples /// Quantization & write sub band samples
@ -740,6 +741,8 @@ static void encode_frame(MpegAudioContext *s,
encode_subbands(s, p, bit_alloc, 0); encode_subbands(s, p, bit_alloc, 0);
#endif #endif
av_assert1(put_bits_left(p) == padding);
/* padding */ /* padding */
for(i=0;i<padding;i++) for(i=0;i<padding;i++)
put_bits(p, 1, 0); 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++) { for(i=0;i<s->nb_channels;i++) {
psycho_acoustic_model(s, smr[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; return ret;
init_put_bits(&s->pb, avpkt->data, avpkt->size); init_put_bits(&s->pb, avpkt->data, avpkt->size);
@ -776,7 +780,6 @@ static int MPA_encode_frame(AVCodecContext *avctx, AVPacket *avpkt,
/* flush */ /* flush */
flush_put_bits(&s->pb); flush_put_bits(&s->pb);
avpkt->size = put_bytes_output(&s->pb);
if (frame->pts != AV_NOPTS_VALUE) if (frame->pts != AV_NOPTS_VALUE)
avpkt->pts = frame->pts - ff_samples_to_time_base(avctx, avctx->initial_padding); avpkt->pts = frame->pts - ff_samples_to_time_base(avctx, avctx->initial_padding);