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| author | Michael Niedermayer <michaelni@gmx.at> | 2014-04-09 18:22:53 +0200 |
|---|---|---|
| committer | Luca Barbato <lu_zero@gentoo.org> | 2014-04-12 13:29:55 +0200 |
| commit | 617a1a98a6be3e59db6fbfc21afab2fb9a049c03 (patch) | |
| tree | 298a82343ab22ddd3fe75a73cca89805b65d9723 | |
| parent | 254c95cdd1b669a722204a4a65974fc2523c8f83 (diff) | |
| download | ffmpeg-617a1a98a6be3e59db6fbfc21afab2fb9a049c03.tar.gz | |
mp3enc: Properly write bitrate value in XING header
Instead of using a fixed bitrate_idx, calculate a matching bitrate for
the XING header.
Using a fixed bitrate_idx causes tools such as file(1) and mediainfo(1)
to report wrong bitrate and bitrate mode when using CBR.
Bug-Id: https://bugs.debian.org/736088
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>
| -rw-r--r-- | libavformat/mp3enc.c | 46 |
1 files changed, 39 insertions, 7 deletions
diff --git a/libavformat/mp3enc.c b/libavformat/mp3enc.c index 46889fc134..932625864f 100644 --- a/libavformat/mp3enc.c +++ b/libavformat/mp3enc.c @@ -119,8 +119,11 @@ static void mp3_write_xing(AVFormatContext *s) MPADecodeHeader mpah; int srate_idx, i, channels; int bitrate_idx; + int best_bitrate_idx; + int best_bitrate_error = INT_MAX; int xing_offset; int ver = 0; + int lsf, bytes_needed; if (!s->pb->seekable || !mp3->write_xing) return; @@ -150,21 +153,51 @@ static void mp3_write_xing(AVFormatContext *s) return; } - /* 64 kbps frame, should be large enough */ - bitrate_idx = (ver == 3) ? 5 : 8; - /* dummy MPEG audio header */ header = 0xff << 24; // sync header |= (0x7 << 5 | ver << 3 | 0x1 << 1 | 0x1) << 16; // sync/audio-version/layer 3/no crc*/ - header |= (bitrate_idx << 4 | srate_idx << 2) << 8; + header |= (srate_idx << 2) << 8; header |= channels << 6; + + lsf = !((header & (1 << 20) && header & (1 << 19))); + + xing_offset = xing_offtbl[ver != 3][channels == 1]; + bytes_needed = 4 // header + + xing_offset + + 4 // xing tag + + 4 // frames/size/toc flags + + 4 // frames + + 4 // size + + XING_TOC_SIZE; // toc + + for (bitrate_idx = 1; bitrate_idx < 15; bitrate_idx++) { + int bit_rate = 1000 * avpriv_mpa_bitrate_tab[lsf][3 - 1][bitrate_idx]; + int error = FFABS(bit_rate - codec->bit_rate); + + if (error < best_bitrate_error){ + best_bitrate_error = error; + best_bitrate_idx = bitrate_idx; + } + } + + for (bitrate_idx = best_bitrate_idx; bitrate_idx < 15; bitrate_idx++) { + int32_t mask = bitrate_idx << (4 + 8); + header |= mask; + + avpriv_mpegaudio_decode_header(&mpah, header); + + if (bytes_needed <= mpah.frame_size) + break; + + header &= ~mask; + } + avio_wb32(s->pb, header); avpriv_mpegaudio_decode_header(&mpah, header); av_assert0(mpah.frame_size >= XING_MAX_SIZE); - xing_offset = xing_offtbl[ver != 3][codec->channels == 1]; ffio_fill(s->pb, 0, xing_offset); mp3->xing_offset = avio_tell(s->pb); ffio_wfourcc(s->pb, "Xing"); @@ -180,8 +213,7 @@ static void mp3_write_xing(AVFormatContext *s) for (i = 0; i < XING_TOC_SIZE; i++) avio_w8(s->pb, 255 * i / XING_TOC_SIZE); - mpah.frame_size -= 4 + xing_offset + 4 + 4 + 4 + 4 + XING_TOC_SIZE; - ffio_fill(s->pb, 0, mpah.frame_size); + ffio_fill(s->pb, 0, mpah.frame_size - bytes_needed); } /* |