AC3 Audio - correct hmt file settings

MontysEvilTwin

Well-Known Member
I have recently copied some recordings from my Panasonic DVD/ HDD/ VHS recorder to an HDR-FOX T2. These recordings are comprised of several VOB files with MPEG2 video and AC3 audio. I used TSMuxer GUI to join the VOB files and remux them to a single m2ts file per recording. I then created sidecar files using the Sidecar package on the HDR-FOX T2, or alternatively used AV2-HDR T2 on a Windows PC. In both cases, the recordings play on the HDR-FOX T2 without sound. I found that changing the value at offset 0x0488 in the hmt file to zero enables audio playback, but it is a bit of a bodge. I also noticed that if you press the audio button on the remote control, you get a message "The audio is not available". This disappears on its own or if you press the OK button, but if you press the audio button again while the message is on screen it makes the unit crash and reboot. Looking at the hmt file format document on the wiki I have been unable to figure out where the problem is.

I also made a short recording on the HDR-FOX to investigate further (info from ffmpeg):
Code:
    Stream #0:0[0x709]: Video: mpeg2video (Main) ([2][0][0][0] / 0x0002), yuv420p(tv), 720x576 [SAR 64:45 DAR 16:9], max. 2702 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc                                 
    Stream #0:1[0x70a](eng): Audio: mp2 ([4][0][0][0] / 0x0004), 48000 Hz, stereo, s16p, 192 kb/s                                                              
    Stream #0:2[0x70b](eng): Audio: mp2 ([4][0][0][0] / 0x0004), 48000 Hz, mono, s16p, 64 kb/s (visual impaired)                                              
    Stream #0:3[0x727](eng): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006)
and then copied it with ffmpeg, transcoding the audio to AC3:
Code:
    Stream #0:0[0x100]: Video: mpeg2video (Main) ([2][0][0][0] / 0x0002), yuv420p(tv), 720x576 [SAR 64:45 DAR 16:9], max. 2736 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc
    Stream #0:1[0x101](eng): Audio: ac3 ([129][0][0][0] / 0x0081), 48000 Hz, stereo, fltp, 192 kb/s
    Stream #0:2[0x102](eng): Audio: ac3 ([129][0][0][0] / 0x0081), 48000 Hz, mono, fltp, 96 kb/s (visual impaired)                                            
    Stream #0:3[0x103](eng): Subtitle: dvb_subtitle ([6][0][0][0] / 0x0006)
The ffmpeg processed file (plus sidecar-generated hmt and nts files) also played without audio. Modifying the hmt file (at offset 0x0488, see above) enabled audio playback but again, pressing the audio button gave the "The audio is not available message". In this case it was only possible to play the audio description track (info from sidecar):
Code:
/media/My Video/BF2.ts
Duration 345 seconds.
Format SD MPEG, 720 x 576. N/A.
Video ID $0100.
Audio ID $0102, Type AC3.
Audio Desc ID $0000, not present.
Sub-titles ID $0103.
PMT ID $1000.
Prog ID $0001.
No EPG information available.
Without sidecar files the main audio track is played. Changing the audio ID in the hmt file (2byte entry at offset 0x049c) makes the main track playable on the unit, but it is still not possible to choose audio tracks. Is it possible to fix this by editing the hmt file?
 
Top