* [FFmpeg-devel] [PATCH] Fix WAV bitrate calculation when bits_per_coded_sample != 8
@ 2025-11-17 13:01 Erdinc Kaya via ffmpeg-devel
2025-11-25 1:24 ` [FFmpeg-devel] " Michael Niedermayer via ffmpeg-devel
2025-11-25 2:15 ` James Almer via ffmpeg-devel
0 siblings, 2 replies; 3+ messages in thread
From: Erdinc Kaya via ffmpeg-devel @ 2025-11-17 13:01 UTC (permalink / raw)
To: ffmpeg-devel; +Cc: Erdinc Kaya
- Correctly scale bitrate by bits_per_coded_sample instead of assuming 8
bits per byte.
- Prevents wrong bitrate reports for 16-bit PCM WAV files.
Signed-off-by: Erdinc Kaya <erdinc@veed.io>
---
libavformat/riffdec.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/libavformat/riffdec.c b/libavformat/riffdec.c
index 30835d5f36..d63edc6377 100644
--- a/libavformat/riffdec.c
+++ b/libavformat/riffdec.c
@@ -130,6 +130,10 @@ int ff_get_wav_header(AVFormatContext *s,
AVIOContext *pb,
par->bits_per_coded_sample = avio_rb16(pb);
}
}
+
+ if (par->bits_per_coded_sample)
+ bitrate *= 8.0 / par->bits_per_coded_sample;
+
if (id == 0xFFFE) {
par->codec_tag = 0;
} else {
--
2.43.0
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^ permalink raw reply [flat|nested] 3+ messages in thread* [FFmpeg-devel] Re: [PATCH] Fix WAV bitrate calculation when bits_per_coded_sample != 8
2025-11-17 13:01 [FFmpeg-devel] [PATCH] Fix WAV bitrate calculation when bits_per_coded_sample != 8 Erdinc Kaya via ffmpeg-devel
@ 2025-11-25 1:24 ` Michael Niedermayer via ffmpeg-devel
2025-11-25 2:15 ` James Almer via ffmpeg-devel
1 sibling, 0 replies; 3+ messages in thread
From: Michael Niedermayer via ffmpeg-devel @ 2025-11-25 1:24 UTC (permalink / raw)
To: FFmpeg development discussions and patches; +Cc: Michael Niedermayer
[-- Attachment #1.1: Type: text/plain, Size: 6381 bytes --]
On Mon, Nov 17, 2025 at 02:01:19PM +0100, Erdinc Kaya via ffmpeg-devel wrote:
> - Correctly scale bitrate by bits_per_coded_sample instead of assuming 8
> bits per byte.
> - Prevents wrong bitrate reports for 16-bit PCM WAV files.
>
> Signed-off-by: Erdinc Kaya <erdinc@veed.io>
> ---
> libavformat/riffdec.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/libavformat/riffdec.c b/libavformat/riffdec.c
> index 30835d5f36..d63edc6377 100644
> --- a/libavformat/riffdec.c
> +++ b/libavformat/riffdec.c
> @@ -130,6 +130,10 @@ int ff_get_wav_header(AVFormatContext *s, AVIOContext
> *pb,
> par->bits_per_coded_sample = avio_rb16(pb);
> }
> }
> +
> + if (par->bits_per_coded_sample)
> + bitrate *= 8.0 / par->bits_per_coded_sample;
> +
> if (id == 0xFFFE) {
> par->codec_tag = 0;
> } else {
breaks fate
--- ./tests/ref/seek/acodec-adpcm-ms-trellis 2025-11-19 00:07:58.826436074 +0100
+++ tests/data/fate/seek-acodec-adpcm-ms-trellis 2025-11-25 02:24:33.522013997 +0100
@@ -2,52 +2,52 @@
ret: 0 st:-1 flags:0 ts:-1.000000
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 90 size: 4096
ret: 0 st:-1 flags:1 ts: 1.894167
-ret: 0 st: 0 flags:1 dts: 1.856009 pts: 1.856009 pos: 29786 size: 4096
+ret: 0 st: 0 flags:1 dts: 1.888005 pts: 1.888005 pos: 60506 size: 4096
ret: 0 st: 0 flags:0 ts: 0.788345
-ret: 0 st: 0 flags:1 dts: 0.831995 pts: 0.831995 pos: 13402 size: 4096
+ret: 0 st: 0 flags:1 dts: 0.800000 pts: 0.800000 pos: 25690 size: 4096
ret: 0 st: 0 flags:1 ts:-0.317506
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 90 size: 4096
ret: 0 st:-1 flags:0 ts: 2.576668
-ret: 0 st: 0 flags:1 dts: 2.623991 pts: 2.623991 pos: 42074 size: 4096
+ret: 0 st: 0 flags:1 dts: 2.591995 pts: 2.591995 pos: 83034 size: 4096
ret: 0 st:-1 flags:1 ts: 1.470835
-ret: 0 st: 0 flags:1 dts: 1.408005 pts: 1.408005 pos: 22618 size: 4096
+ret: 0 st: 0 flags:1 dts: 1.440000 pts: 1.440000 pos: 46170 size: 4096
ret: 0 st: 0 flags:0 ts: 0.365011
-ret: 0 st: 0 flags:1 dts: 0.383991 pts: 0.383991 pos: 6234 size: 4096
+ret: 0 st: 0 flags:1 dts: 0.383991 pts: 0.383991 pos: 12378 size: 4096
ret: 0 st: 0 flags:1 ts:-0.740839
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 90 size: 4096
ret: 0 st:-1 flags:0 ts: 2.153336
-ret: 0 st: 0 flags:1 dts: 2.176009 pts: 2.176009 pos: 34906 size: 4096
+ret: 0 st: 0 flags:1 dts: 2.176009 pts: 2.176009 pos: 69722 size: 4096
ret: 0 st:-1 flags:1 ts: 1.047503
-ret: 0 st: 0 flags:1 dts: 1.023991 pts: 1.023991 pos: 16474 size: 4096
+ret: 0 st: 0 flags:1 dts: 1.023991 pts: 1.023991 pos: 32858 size: 4096
ret: 0 st: 0 flags:0 ts:-0.058322
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 90 size: 4096
ret: 0 st: 0 flags:1 ts: 2.835828
-ret: 0 st: 0 flags:1 dts: 2.816009 pts: 2.816009 pos: 45146 size: 4096
+ret: 0 st: 0 flags:1 dts: 2.816009 pts: 2.816009 pos: 90202 size: 4096
ret: 0 st:-1 flags:0 ts: 1.730004
-ret: 0 st: 0 flags:1 dts: 1.791995 pts: 1.791995 pos: 28762 size: 4096
+ret: 0 st: 0 flags:1 dts: 1.760000 pts: 1.760000 pos: 56410 size: 4096
ret: 0 st:-1 flags:1 ts: 0.624171
-ret: 0 st: 0 flags:1 dts: 0.576009 pts: 0.576009 pos: 9306 size: 4096
+ret: 0 st: 0 flags:1 dts: 0.608005 pts: 0.608005 pos: 19546 size: 4096
ret: 0 st: 0 flags:0 ts:-0.481655
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 90 size: 4096
ret: 0 st: 0 flags:1 ts: 2.412494
-ret: 0 st: 0 flags:1 dts: 2.368005 pts: 2.368005 pos: 37978 size: 4096
+ret: 0 st: 0 flags:1 dts: 2.400000 pts: 2.400000 pos: 76890 size: 4096
ret: 0 st:-1 flags:0 ts: 1.306672
-ret: 0 st: 0 flags:1 dts: 1.343991 pts: 1.343991 pos: 21594 size: 4096
+ret: 0 st: 0 flags:1 dts: 1.311995 pts: 1.311995 pos: 42074 size: 4096
ret: 0 st:-1 flags:1 ts: 0.200839
-ret: 0 st: 0 flags:1 dts: 0.191995 pts: 0.191995 pos: 3162 size: 4096
+ret: 0 st: 0 flags:1 dts: 0.191995 pts: 0.191995 pos: 6234 size: 4096
ret: 0 st: 0 flags:0 ts:-0.904989
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 90 size: 4096
ret: 0 st: 0 flags:1 ts: 1.989184
-ret: 0 st: 0 flags:1 dts: 1.983991 pts: 1.983991 pos: 31834 size: 4096
+ret: 0 st: 0 flags:1 dts: 1.983991 pts: 1.983991 pos: 63578 size: 4096
ret: 0 st:-1 flags:0 ts: 0.883340
-ret: 0 st: 0 flags:1 dts: 0.896009 pts: 0.896009 pos: 14426 size: 4096
+ret: 0 st: 0 flags:1 dts: 0.896009 pts: 0.896009 pos: 28762 size: 4096
ret: 0 st:-1 flags:1 ts:-0.222493
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 90 size: 4096
ret: 0 st: 0 flags:0 ts: 2.671678
-ret: 0 st: 0 flags:1 dts: 2.688005 pts: 2.688005 pos: 43098 size: 4096
+ret: 0 st: 0 flags:1 dts: 2.688005 pts: 2.688005 pos: 86106 size: 4096
ret: 0 st: 0 flags:1 ts: 1.565850
-ret: 0 st: 0 flags:1 dts: 1.536009 pts: 1.536009 pos: 24666 size: 4096
+ret: 0 st: 0 flags:1 dts: 1.536009 pts: 1.536009 pos: 49242 size: 4096
ret: 0 st:-1 flags:0 ts: 0.460008
-ret: 0 st: 0 flags:1 dts: 0.511995 pts: 0.511995 pos: 8282 size: 4096
+ret: 0 st: 0 flags:1 dts: 0.480000 pts: 0.480000 pos: 15450 size: 4096
ret: 0 st:-1 flags:1 ts:-0.645825
ret: 0 st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos: 90 size: 4096
Test seek-acodec-adpcm-ms-trellis failed. Look at tests/data/fate/seek-acodec-adpcm-ms-trellis.err for details.
make: *** [tests/Makefile:321: fate-seek-acodec-adpcm-ms-trellis] Error 1
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Let us carefully observe those good qualities wherein our enemies excel us
and endeavor to excel them, by avoiding what is faulty, and imitating what
is excellent in them. -- Plutarch
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^ permalink raw reply [flat|nested] 3+ messages in thread* [FFmpeg-devel] Re: [PATCH] Fix WAV bitrate calculation when bits_per_coded_sample != 8
2025-11-17 13:01 [FFmpeg-devel] [PATCH] Fix WAV bitrate calculation when bits_per_coded_sample != 8 Erdinc Kaya via ffmpeg-devel
2025-11-25 1:24 ` [FFmpeg-devel] " Michael Niedermayer via ffmpeg-devel
@ 2025-11-25 2:15 ` James Almer via ffmpeg-devel
1 sibling, 0 replies; 3+ messages in thread
From: James Almer via ffmpeg-devel @ 2025-11-25 2:15 UTC (permalink / raw)
To: ffmpeg-devel; +Cc: James Almer
[-- Attachment #1.1.1: Type: text/plain, Size: 1432 bytes --]
On 11/17/2025 10:01 AM, Erdinc Kaya via ffmpeg-devel wrote:
> - Correctly scale bitrate by bits_per_coded_sample instead of assuming 8
> bits per byte.
When is a byte not 8 bits?
> - Prevents wrong bitrate reports for 16-bit PCM WAV files.
Do you have a sample that gets the wrong bitrate? I generated one just
now, a 1 second 44100Hz 16bit stereo pcm wav file, and it gave me the
correct bitrate of 1411 kb/s.
This function reads bitrate from a coded value in the container,
BytePerSec, which is converted to bits. So not sure why you think it
needs to be altered.
>
> Signed-off-by: Erdinc Kaya <erdinc@veed.io>
> ---
> libavformat/riffdec.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/libavformat/riffdec.c b/libavformat/riffdec.c
> index 30835d5f36..d63edc6377 100644
> --- a/libavformat/riffdec.c
> +++ b/libavformat/riffdec.c
> @@ -130,6 +130,10 @@ int ff_get_wav_header(AVFormatContext *s,
> AVIOContext *pb,
> par->bits_per_coded_sample = avio_rb16(pb);
> }
> }
> +
> + if (par->bits_per_coded_sample)
> + bitrate *= 8.0 / par->bits_per_coded_sample;
bits_per_coded_sample is going to be 16 for a 16 bit pcm sample,
clearly, so this here will halve the value in bitrate.
> +
> if (id == 0xFFFE) {
> par->codec_tag = 0;
> } else {
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^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2025-11-25 2:16 UTC | newest]
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2025-11-17 13:01 [FFmpeg-devel] [PATCH] Fix WAV bitrate calculation when bits_per_coded_sample != 8 Erdinc Kaya via ffmpeg-devel
2025-11-25 1:24 ` [FFmpeg-devel] " Michael Niedermayer via ffmpeg-devel
2025-11-25 2:15 ` James Almer via ffmpeg-devel
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